Oxygenate

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In the liquid fuel industry, oxygenates are hydrocarbon-derived fuel additives containing at least one oxygen atom [1] to promote complete combustion. [2] Absent oxygenates, fuel combustion is usually incomplete, and the exhaust stream pollutes the air with carbon monoxide, soot particles, aromatic and polyaromatic hydrocarbons, and nitrated polyaromatic hydrocarbons. [3]

Contents

The most common oxygenates are either alcohols or ethers, but ketones and aldehydes are also included in this distinction. [4] Carboxylic acids and esters can be grouped with oxygenates in the simple definition that they contain at least one oxygen atom. [4] However, they are usually unwanted in oils, and therefore likely fuels, due to their environmental toxicity and tendency to cause catalyst poisoning and corrosion during oil production and refining. [5]

In the United States

In the United States, the Environmental Protection Agency (EPA) had authority to mandate that minimum proportions of oxygenates be added to automotive gasoline on regional and seasonal basis from 1992 until 2006 in an attempt to reduce air pollution, in particular ground-level ozone and smog. As of 2023, the EPA continues to require the use of oxygenated gasoline in certain areas during winter to regulate carbon monoxide emissions; however, the programs to fulfill its conditions are implemented by the states. In addition to this North American automakers from 2006 onwards promoted a blend of 85% ethanol and 15% gasoline, marketed as E85, and their flex-fuel vehicles, e.g. GM's Live Green, Go Yellow campaign. US Corporate Average Fuel Economy (CAFE) standards give an artificial 54% fuel efficiency bonus to vehicles capable of running on 85% alcohol blends over vehicles not adapted to run on 85% alcohol blends. [6] There is also alcohols' intrinsically cleaner combustion, however due to its lower energy density it is not capable of producing as much energy per gallon as gasoline. Much gasoline[ citation needed ] sold in the United States is blended with up to 10% of an oxygenating agent. This is known as oxygenated fuel and often (but not entirely correctly, as there are reformulated gasolines without oxygenate) as reformulated gasoline. Methyl tert-butyl ether (MTBE) was the most common fuel additive in the United States, prior to government mandated use of ethanol. Typically, gasoline with added MTBE is called reformulated gasoline, while gasoline with ethanol is called oxygenated gasoline. [7]

Related Research Articles

<span class="mw-page-title-main">Ether</span> Organic compounds made of alkyl/aryl groups bound to oxygen (R–O–R)

In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom bonded to two organyl groups. They have the general formula R−O−R′, where R and R′ represent the organyl groups. Ethers can again be classified into two varieties: if the organyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether". Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.

<span class="mw-page-title-main">Gasoline</span> Liquid fuel derived from petroleum

Gasoline or petrol is a petrochemical product characterized as a transparent, yellowish, and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When formulated as a fuel for engines, gasoline is chemically composed of organic compounds derived from the fractional distillation of petroleum and later chemically enhanced with gasoline additives. It is a high-volume profitable product produced in crude oil refineries.

Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4H9OH, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a butyl or isobutyl group linked to a hydroxyl group (sometimes represented as BuOH, sec-BuOH, i-BuOH, and t-BuOH). These are 1-butanol, two stereoisomers of sec-butyl alcohol, isobutanol and tert-butyl alcohol. Butanol is primarily used as a solvent and as an intermediate in chemical synthesis, and may be used as a fuel. Biologically produced butanol is called biobutanol, which may be n-butanol or isobutanol.

<span class="mw-page-title-main">Isobutane</span> Chemical compound

Isobutane, also known as i-butane, 2-methylpropane or methylpropane, is a chemical compound with molecular formula HC(CH3)3. It is an isomer of butane. Isobutane is a colorless, odorless gas. It is the simplest alkane with a tertiary carbon atom. Isobutane is used as a precursor molecule in the petrochemical industry, for example in the synthesis of isooctane.

<span class="mw-page-title-main">Biofuel</span> Type of biological fuel

Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and possible deforestation and biodiversity loss as a result of biofuel production.

Methyl <i>tert</i>-butyl ether Chemical compound

Methyl tert-butyl ether (MTBE), also known as tert-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water. Primarily used as a fuel additive, MTBE is blended into gasoline to increase its octane rating and knock resistance, and reduce unwanted emissions.

<span class="mw-page-title-main">Liquid fuel</span> Liquids that can be used to create energy

Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. It is the fumes of liquid fuels that are flammable instead of the fluid. Most liquid fuels in widespread use are derived from fossil fuels; however, there are several types, such as hydrogen fuel, ethanol, and biodiesel, which are also categorized as a liquid fuel. Many liquid fuels play a primary role in transportation and the economy.

Ethyl <i>tert</i>-butyl ether Oxygenate gasoline additive in the production of gasoline from crude oil

Ethyl tertiary-butyl ether (ETBE), also known as ethyl tert-butyl ether, is commonly used as an oxygenate gasoline additive in the production of gasoline from crude oil. ETBE offers equal or greater air quality benefits than ethanol, while being technically and logistically less challenging. Unlike ethanol, ETBE does not induce evaporation of gasoline, which is one of the causes of smog, and does not absorb moisture from the atmosphere.

<span class="mw-page-title-main">Isobutylene</span> Unsaturated hydrocarbon compound (H2C=C(CH3)2)

Isobutylene is a hydrocarbon with the chemical formula (CH3)2C=CH2. It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value.

<i>tert</i>-Butyl alcohol Chemical compound

tert-Butyl alcohol is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). Its isomers are 1-butanol, isobutanol, and butan-2-ol. tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor. It is miscible with water, ethanol and diethyl ether.

The United States produces mainly biodiesel and ethanol fuel, which uses corn as the main feedstock. The US is the world's largest producer of ethanol, having produced nearly 16 billion gallons in 2017 alone. The United States, together with Brazil accounted for 85 percent of all ethanol production, with total world production of 27.05 billion gallons. Biodiesel is commercially available in most oilseed-producing states. As of 2005, it was somewhat more expensive than fossil diesel, though it is still commonly produced in relatively small quantities, in comparison to petroleum products and ethanol fuel.

An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which auto-ignition occurs. The mixture known as gasoline or petrol, when used in high compression internal combustion engines, has a tendency to knock and/or to ignite early before the correctly timed spark occurs.

The molecular formula C6H14O may refer to:

<i>tert</i>-Amyl alcohol Chemical compound

tert-Amyl alcohol (TAA) or 2-methylbutan-2-ol (2M2B), is a branched pentanol.

The MTBE controversy concerns methyl tert-butyl ether (MTBE), a gasoline additive that replaced tetraethyllead. MTBE is an oxygenate and raises gasoline's octane number. Its use declined in the United States in response to environmental and health concerns. It has polluted groundwater due to MTBE-containing gasoline being spilled or leaked at gas stations. MTBE spreads more easily underground than other gasoline components due to its higher solubility in water. Cost estimates for removing MTBE from groundwater and contaminated soil range from $1 billion to $30 billion, including removing the compound from aquifers and municipal water supplies, and replacing leaky underground oil tanks. Who will pay for remediation is controversial. In one case, the cost to oil companies to clean up the MTBE in wells belonging to the city of Santa Monica, California is estimated to exceed $200 million.

tert-Amyl methyl ether (TAME) is an ether used as a fuel oxygenate. TAME derives from C5 distillation fractions of naphtha. It has an ethereous odor. Unlike most ethers, it does not require a stabilizer as it does not form peroxides on storage.

M85 is a fuel consisting of 85% methanol and 15% gasoline (petrol). It is a potential alternative to traditional gasoline and ethanol. M85 is similar to E85, but cannot be used in vehicles designed for E85. Although it is similar in composition, M85 is not as well known as its ethanol counterpart. Despite these issues, methanol is considered a viable alternative fuel as it contains high levels of hydrogen.

<i>tert</i>-Amyl ethyl ether Chemical compound

tert-Amyl ethyl ether (TAEE) is a chemical compound, classified as an ether, with the molecular formula C7H16O. It is used as an additive in gasoline fuels as an oxygenate and also as a solvent in organic chemistry.

<span class="mw-page-title-main">Reformulated Blendstock for Oxygenate Blending</span>

Reformulated Blendstock for Oxygenate Blending (RBOB) is a gasoline futures contract traded on the New York Mercantile Exchange (NYMEX). It is the benchmark futures contract for wholesale gasoline in the United States.

References

  1. ↑ US EPA, OAR (7 August 2015). "Gasoline Winter Oxygenates". www.epa.gov. Retrieved 17 March 2024.
  2. ↑ "Oxygenate". Merriam-Webster online. 2 March 2024. Retrieved 17 March 2024.
  3. ↑ Inal, Fikret; Senkan, Selim M. (2002). "Effects of oxygenate additives on polycyclic aromatic hydrocarbons(pahs) and soot formation". Combustion Science and Technology. 174 (9): 1–19. CiteSeerX   10.1.1.524.1105 . doi:10.1080/00102200290021353. S2CID   56015797.
  4. 1 2 Yeboah, Isaac; Feng, Xiang; Rout, Kumar R.; Chen, De (27 October 2021). "Versatile One-Pot Tandem Conversion of Biomass-Derived Light Oxygenates into High-Yield Jet Fuel Range Aromatics". Industrial & Engineering Chemistry Research. 60 (42): 15095–15105. doi: 10.1021/acs.iecr.1c02994 . ISSN   0888-5885.
  5. ↑ Ni, Wei; Zhu, Gangtian; Liu, Fei; Li, Zhiyong; Xie, Can; Han, Yuanjia (19 August 2021). "Carboxylic Acids in Petroleum: Separation, Analysis, and Geochemical Significance". Energy & Fuels. 35 (16): 12828–12844. doi:10.1021/acs.energyfuels.1c01518. ISSN   0887-0624.
  6. ↑ "Code of Federal Regulations, title 40, part 600, section 600.510-93". United States Government Printing Office. 1 August 2005.[ permanent dead link ]
  7. ↑ Lidderdale, Tancred (6 March 2000). "MTBE, Oxygenates, and Motor Gasoline" (PDF). Energy Information Administration.

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