Fuel ethers: MTBE, ETBE, TAME and TAEE

Emission standards are getting more and more strict, they might vary from country to country, but there is a clear trend to reduce the air pollution globally. Emissions from cars are one of the major pollutants of the air. After the ban of lead alkyl antiknock compounds in the 1990s oxygenates have been introduced as a replacement and as octane boosters in many areas in the world. At the same time these octane boosters allowed the reduction of emissions such as carbon monoxide and ozone.

In the early 2000s, MTBE (Methyl tertiary-butyl ether) was detected in the US in groundwater which lead finally to the replacement of MTBE by isooctane and direct blends of bioethanol into gasoline. In Europe bioethanol as a renewable fuel was mainly introduced through tax incentives generally by replacing MTBE and TAME with ETBE and TAEE, or in other words by replacing methanol in the oxygenate by ethanol.

The octane number is an expression for the antiknock property of a gasoline. The octane number of gasoline can be increased by adding a certain percentage of oxygenates such as MTBE (Methyl tertiary-butyl ether), ETBE (Ethyl tertiary-butyl ether), TAME (Tertiary amyl methyl ether), or TAEE (Tertiary amyl ethyl ether).

Reactions

Generally the reaction of an olefin with an alcohol under acidic conditions is exothermic. The reaction happens already at moderate temperatures. The reaction is extremely selective to isobutylene, butane and butadiene are virtually unaffected. TREVERLYST catalysts have been developed to assure the highest conversion rates at the lowest temperatures possible.

MTBE

ETBE

TAME

Recommended catalysts

TREVER®\|LYST CAT350	Standard catalyst for etherification reactions. High selectivity, excellent stability against fouling
TREVER®\|LYST CAT351	Highest productivity, lifetime and conversion rate
TREVER®\|LYST CAT352	Optimal catalyst for C5-C5 ethers such as TAME. Highest surface area and pore volume for improved activity for C5 and C6 etherification
Metal doped catalysts	For TAME and other reactions where a trifunctional catalyst is required

Note: Special particle size might be required for some reactor configurations.