MTBE

Methyl tert-butyl ether: a petrol octane booster made from methanol and isobutylene, still widely used in Asia and Latin America but banned in the US.

Commodity chemicals · Methanol & oxygenates · No. 34

• Single chemical
• Feedstock: Oil, gas or coal
• about 30-33 Mt a year (2024, indicative, basis: 10.8% of 111.8 Mt methanol at 0.364 t methanol per t MTBE; includes some TAME)
• 1.5 t CO₂e per t
• HS 290919

Banned in the United States after it tainted groundwater, MTBE still boosts the octane of petrol across Asia and Latin America.

Chart: Illustration: MTBE

Where it comes from

Chart: Map of where it comes from

Methanol reacts with isobutylene from refinery or cracker C4 streams, or from dehydrogenated butane, over an acidic resin. By weight it is about 36% methanol and 64% isobutylene.

Three things to know

1. About 94% of MTBE goes into petrol, where its blending octane of about 110-118 helped refiners phase out lead.
2. It takes about 11% of world methanol, roughly 12 Mt a year in 2024.
3. MTBE dissolves easily in water and breaks down slowly, so US states banned it and federal oxygenate rules ended in 2006.

The journey

1. 1 C4 streamsIsobutylene from refinery or cracker C4s
2. 2 MethanolAbout 0.364 t per tonne MTBE
3. 3 EtherificationAcidic resin at 40-90 C, 99% conversion
4. 4 Product tankersUS Gulf to Mexico, Gulf to Europe
5. 5 Petrol blendingAdded at 5-15% by volume

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