Technology

MTBE is produced by the Liquid-Phase Addition of Methanol to Isobutene. The Reaction is exothermic and is carried out over Acidic Iion-Exchange Resins. Isobutene (IB) may vary from as low as 10±15% by weight in Streams from FCC, up to 50±55% by weight in Streams from Dehydrogenation Units. Since the Reaction is exothermic and limited by the chemical equilibrium, in order to maximize the Isobutene Conversion, the Reactor outlet temperature is maintained as low as allowed by the Catalyst activity. Operating temperatures range between 408°C and 808°C. Selectivity to MTBE is usually higher than 99%; the only by-products are Diisobutenes (DIB), Dimethylether (DME), tert-Butyl Alcohol (TBA), and if linear Butenes are present, their corresponding Ethers, mainly Methyl-sec-Butyl-Ether (MSBE). In the Snamprogetti process, the Etherification is generally carried out in two Reactors with intermediate Product removal.