gasoline specs such as RVP. Essentially all companies in North America use
ethanol in the gasoline blend by Federal mandate.
Much success in reducing aromatics in gasoline to date however has been in the
production and blending of oxygenated compounds into the gasoline pool, but
mostly outside the USA. A press release by a number of companies in 1990 is
quoted as follows:
• Adding oxygenates reduces the amount of exhaust emissions (hydrocarbons and
carbon monoxide) and the benefits have been quantified.
• Changing the level of olefins in gasoline does not have much of an impact on
vehicle exhaust emission.
• Reducing aromatics and/or boiling range of gasoline can either reduce or
increase exhaust emissions depending upon vehicle type.
Oxygenates are ether compounds derived from their respective alcohol. There
are three candidates of these ethers to meet the gasoline requirements. These are:
• Methyl tertiary butyl ether (MTBE)
• Ethyl tertiary butyl ether (ETBE)
• Tertiary amyl methyl ether (TAME)
Of these three candidates MTBE is the one that has been used more extensively
to meet all the gasoline pool objectives. This compound has the blending quality of
109 octane, an RVP blending of 8–10 psi, and a boiling point of 131
F.
ETBE octane blending properties seem to be slightly better than those of MTBE
and so does its RVP blending qualities. The ethanol feed stream of course is not as
readily available as methanol and requires a separate production unit, often by
means of fermentation of organic materials.
TAME has an average octane number of 104 and an RVP blending of 3–5 psi.
Except for the lower octane value, TAME has similar blending properties to ETBE.
The ether in this case is formed by the reaction of 2-methyl-2-butene and 2-methyl1-butene olefin feed and methanol. Commercial plants operate in the UK and parts
of Europe producing TAME. The compound is used in Europe as a gasoline product
and not as a gasoline blend stock. The front end of a cracked gasoline stream is used
in this manufacture to provide the olefin.
Use of MTBE has been phased out in the USA because of groundwater contamination (MTBE has a very unpleasant smell) but is still in use in Europe and
elsewhere. However, emphasis on the use of renewable resources in Europe has
prompted a gradual shift from MTBE to ETBE.
The Production of Ethers for Gasoline Blending
There are several licensed processes for the production of methyl tertiary butyl
ether by the etherification of a C 4 /C 5 olefin stream and methanol. These processes
42
D.S.J. Jones
ethanol in the gasoline blend by Federal mandate.
Much success in reducing aromatics in gasoline to date however has been in the
production and blending of oxygenated compounds into the gasoline pool, but
mostly outside the USA. A press release by a number of companies in 1990 is
quoted as follows:
• Adding oxygenates reduces the amount of exhaust emissions (hydrocarbons and
carbon monoxide) and the benefits have been quantified.
• Changing the level of olefins in gasoline does not have much of an impact on
vehicle exhaust emission.
• Reducing aromatics and/or boiling range of gasoline can either reduce or
increase exhaust emissions depending upon vehicle type.
Oxygenates are ether compounds derived from their respective alcohol. There
are three candidates of these ethers to meet the gasoline requirements. These are:
• Methyl tertiary butyl ether (MTBE)
• Ethyl tertiary butyl ether (ETBE)
• Tertiary amyl methyl ether (TAME)
Of these three candidates MTBE is the one that has been used more extensively
to meet all the gasoline pool objectives. This compound has the blending quality of
109 octane, an RVP blending of 8–10 psi, and a boiling point of 131
F.
ETBE octane blending properties seem to be slightly better than those of MTBE
and so does its RVP blending qualities. The ethanol feed stream of course is not as
readily available as methanol and requires a separate production unit, often by
means of fermentation of organic materials.
TAME has an average octane number of 104 and an RVP blending of 3–5 psi.
Except for the lower octane value, TAME has similar blending properties to ETBE.
The ether in this case is formed by the reaction of 2-methyl-2-butene and 2-methyl1-butene olefin feed and methanol. Commercial plants operate in the UK and parts
of Europe producing TAME. The compound is used in Europe as a gasoline product
and not as a gasoline blend stock. The front end of a cracked gasoline stream is used
in this manufacture to provide the olefin.
Use of MTBE has been phased out in the USA because of groundwater contamination (MTBE has a very unpleasant smell) but is still in use in Europe and
elsewhere. However, emphasis on the use of renewable resources in Europe has
prompted a gradual shift from MTBE to ETBE.
The Production of Ethers for Gasoline Blending
There are several licensed processes for the production of methyl tertiary butyl
ether by the etherification of a C 4 /C 5 olefin stream and methanol. These processes
42
D.S.J. Jones