Octane in gasoline

West European production capacity for MTBE is estimated at 3.61m tonne, unchanged since 1998. In 1999, west European production, at around 3m tonne, represented an 83% operating rate. Consumption was considerably lower at 2.2m tonne. Europe s new gasoline specification, which came into force in January 2000, has lifted consumption to an estimated 2.7m tonne in 2000. MTBE is used to boost octane in gasoline and to promote cleaner burning and reduce harmful vehicle emissions. Demand to meet 2000 gasoline specifications in Europe boosted prices from 250 US dollars/tonne mid-1999 to touch 600 US dollars/tonne fob Rotterdam briefly in June 2000. There is increasing likelihood that the California ban on the use of MTBE, due to come into effect end 2002, will lead to further bans in the US marketplace. 

MTBE is a well known enhancer of the number of octanes in gasoline and as excellent oxygentated fuel additives that decrease carbon monoxide emissions. Therefore, MTBE has been one of the fastest growing chemicals of the past decade. MTBE is produced by reacting methanol with isobutylene from mixed-C4 stream liquid phase over a strong acid ion-exchange resin as catalyst. An excess of methanol is used in order to improve the reaction conversion. This excess has to be separated from the final product. The pervaporation technique, more energy efficient and with lower cost process, has been proposed as alternative to distillation [74],... 

The energy contained in the chemicai bonds of fossii fuels is tapped by combustion reactions, the reverse of photosynthesis. For exampie, octane in gasoline is burned according to the reaction ... 

The trend in d and has also been accompanied by improvements in product quality illustratisd by the increases in gasoline octane numbers and diesel oil cetane numbers. 

Ethers result from the selective addition of methanol or ethanol to the isobutene contained in C4 olefin fractions. Ethers are used as components in gasoline because of their high octane blending value (RON and MON). 

Ethers, such as MTBE and methyl / fZ-amyl ether (TAME) are made by a catalytic process from methanol (qv) and the corresponding isomeric olefin. These ethers have excellent octane values and compete on an economic basis with alkylation for inclusion in gasoline. Another ether, ethyl tert-huty ether (ETBE) is made from ethanol (qv) and isobutylene (see Butylenes). The cost and economic driving forces to use ETBE vs MTBE or TAME ate a function of the raw material costs and any tax incentives that may be provided because of the ethanol that is used to produce it. 

Amylenes. Amylenes (C monoolefins) produce alkylates with a research octane in the range of 90—93. In the past, amylenes have not been used widely as an industrial alkylation charge, although in specific instances, alkylation with amylenes has been practiced (23). In the future, alkylation with amylenes will become more important as limits are placed on the vapor pressure and light olefin content of gasolines. 

Some efforts were made in the early 1980s to employ isobutyl and -butyl alcohols as octane extenders in gasoline. American Methyl Corporation in 1983, under a special waiver of the 1977 Clean Air Act (24), marketed a gasoline blend called Petrocoal containing methanol and a C-4 alcohol which was principally isobutyl alcohol. About 10,000 t of isobutyl and 5000 t of -butyl alcohol were consumed in this appHcation (10). In 1984, the EPA attempted to rescind this waiver and demand for isobutyl alcohol as a gasoline additive dropped to 136.3 t (10). Ultimately, the waiver was rescinded and no isobutyl or -butyl alcohol has been marketed for gasoline additive end use since 1984. 

Isomerization. Isomerization of low octane and / -paraffins in gasoline streams into higher octane branched isomers is an important... 

The illustrated unit can be used to study vapor-phase reforming of kerosene fractions to high octane gasoline, or hydrogenation of benzene, neat or in gasoline mixtures to cyclohexane and methylcyclopentane. In liquid phase experiments hydrotreating of distillate fractions can be studied. The so-called Solvent Methanol Process was studied in the liquid phase, where the liquid feed was a solvent only, a white oil fraction. 

The use of acidic chloroaluminates as alternative liquid acid catalysts for the allcy-lation of light olefins with isobutane, for the production of high octane number gasoline blending components, is also a challenge. This reaction has been performed in a continuous flow pilot plant operation at IFP [44] in a reactor vessel similar to that used for dimerization. The feed, a mixture of olefin and isobutane, is pumped continuously into the well stirred reactor containing the ionic liquid catalyst. In the case of ethene, which is less reactive than butene, [pyridinium]Cl/AlCl3 (1 2 molar ratio) ionic liquid proved to be the best candidate (Table 5.3-4). 

An octane rating scale was devised for fuels to quantify their knock resistance. Further research led to cataloguing the antiknock qualities of the myriad individual hydrocarbon species found in gasoline. 

The naphthenes and aromatics both have cyclic (or ring-like) molecular structures and both possess high octane numbers. Napthenes are saturated and aromatics contain alternate double bonds on their ring. They are typically found in gasoline. The naphthenes also are an important part of kerosene. 

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