METHYLALCOHOL (CH₃OH)

Methyl alcohol (methanol) is the first member of the aliphatic alcohol family. It ranks among the top twenty organic chemicals consumed in the U.S. The current world demand for methanol is approximately 25.5 million tons/year (1998) and is expected to reach 30 million tons by the year 2002. The 1994 U.S. production was 10.8 billion pounds. Methanol was originally produced by the destructive distillation of wood (wood alcohol) for charcoal production. Currently, it is mainly produced from synthesis gas.

As a chemical compound, methanol is highly polar, and hydrogen bonding is evidenced by its relatively high boiling temperature (65°C), its high heat of vaporization, and its low volatility. Due to the high oxygen content of methanol (50 wt%), it is being considered as a gasoline blending compound to reduce carbon monoxide and hydrocarbon emissions in automobile exhaust gases. It was also tested for blending with gasolines due to its high octane (RON = 112). During the late seventies and early eighties, many experiments tested the possible use of pure (straight) methanol as an alternative fuel for gasoline cars. Several problems were encountered, however, in its use as a fuel, such as the cold engine startability due to its high vaporization heat (heat of vaporization is 3.7 times that for gasoline), its lower heating value, which is approximately half that of gasoline, and its corrosive properties. The subject has been reviewed by Keller.

 However, methanol is a potential fuel for gas turbines because it burns smoothly and has exceptionally low nitrogen oxide emission levels. Due to the high reactivity of methanol, many chemicals could be derived from it. For example, it could be oxidized to formaldehyde, an important chemical building block, carbonylated to acetic acid, and dehydrated and polymerized to hydrocarbons in the gasoline range (MTG process). Methanol reacts almost quantitatively with isobutene and isoamylenes, producing methyl t-butylether (MTBE) and tertiary amyl methyl ether (TAME), respectively. Both are important gasoline additives for raising the octane number and reducing carbon monoxide and hydrocarbon exhaust emissions. Additionally, much of the current work is centered on the use of shape-selective catalysts to convert methanol to light olefins as a possible future source of ethylene and propylene. The subject has been reviewed by Chang.