Methyl tert-butyl ether (MTBE) is a flammable liquid that has been used as an additive for unleaded gasoline since the 1980s. MTBE increases octane and oxygen levels in gasoline and reduces pollution emissions.

Methyl tertiary-butyl ether (MTBE), also known as methyl tert-butyl ether and tert-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water.

Methyl tert-butyl ether is prepared, and a stream of hydrocarbons containing isobutylene is freed therefrom, by reacting the isobutylene with methanol in a two stage process wherein, in the first stage, a stream of hydrocarbons containing isobutylene and methanol is fed to a primary reaction zone where the isobutylene