Pyrolysis gasoline or pygas is a naphtha-range product with high aromatics content. [1] It is a by-product of high temperature naphtha cracking during ethylene and propylene production, a high octane number mixture that contains aromatics from the aromatization reactions, olefins, and paraffins ranging from C5s to C12s. The mixture has its own CAS Number: 68477-58-7.
Pygas has high potential for use as a gasoline blending mixture and/or as a source of aromatics. Currently, pygas is generally used as a gasoline blending mixture due to its high octane number. [2] Depending on the feedstock used to produce the olefins, steam cracking can produce a benzene-rich liquid by-product called pyrolysis gasoline. Pyrolysis gasoline can be blended with other hydrocarbons as a gasoline additive, or distilled (in BTX process) to separate it into its components, including benzene.
Raw pyrolysis gasoline (RPG, raw pygas) is rich in benzene and is usually subjected to hydrogenation. Hydrogenated pyrolysis gasoline (HPG, hydrogenated pygas) is a common feedstock of BTX plants for benzene and toluene extraction. [3]
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may be similar to that of gasoline or lighter fluid. They occur in a diverse range of molecular structures and phases: they can be gases, liquids, low melting solids or polymers.
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.
Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.
An oil refinery or petroleum refinery is an industrial process plant where petroleum is transformed and refined into products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefied petroleum gas and petroleum naphtha. Petrochemical feedstock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot at or near an oil refinery for the storage of incoming crude oil feedstock as well as bulk liquid products. In 2020, the total capacity of global refineries for crude oil was about 101.2 million barrels per day.
In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon–carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on the temperature and presence of catalysts. Cracking is the breakdown of large hydrocarbons into smaller, more useful alkanes and alkenes. Simply put, hydrocarbon cracking is the process of breaking long-chain hydrocarbons into short ones. This process requires high temperatures.
Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure.
Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like odor.
Catalytic reforming is a chemical process used to convert naphthas from crude oil into liquid products called reformates, which are premium "blending stocks" for high-octane gasoline. The process converts low-octane linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic naphthenes, which are then partially dehydrogenated to produce high-octane aromatic hydrocarbons. The dehydrogenation also produces significant amounts of byproduct hydrogen gas, which is fed into other refinery processes such as hydrocracking. A side reaction is hydrogenolysis, which produces light hydrocarbons of lower value, such as methane, ethane, propane and butanes.
Gas to liquids (GTL) is a refinery process to convert natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons, such as gasoline or diesel fuel. Methane-rich gases are converted into liquid synthetic fuels. Two general strategies exist: (i) direct partial combustion of methane to methanol and (ii) Fischer–Tropsch-like processes that convert carbon monoxide and hydrogen into hydrocarbons. Strategy ii is followed by diverse methods to convert the hydrogen-carbon monoxide mixtures to liquids. Direct partial combustion has been demonstrated in nature but not replicated commercially. Technologies reliant on partial combustion have been commercialized mainly in regions where natural gas is inexpensive.
The Bergius process is a method of production of liquid hydrocarbons for use as synthetic fuel by hydrogenation of high-volatile bituminous coal at high temperature and pressure. It was first developed by Friedrich Bergius in 1913. In 1931 Bergius was awarded the Nobel Prize in Chemistry for his development of high-pressure chemistry.
Fluid catalytic cracking (FCC) is the conversion process used in petroleum refineries to convert the high-boiling point, high-molecular weight hydrocarbon fractions of petroleum into gasoline, alkene gases, and other petroleum products. The cracking of petroleum hydrocarbons was originally done by thermal cracking, now virtually replaced by catalytic cracking, which yields greater volumes of high octane rating gasoline; and produces by-product gases, with more carbon-carbon double bonds, that are of greater economic value than the gases produced by thermal cracking.
Hydrodesulfurization (HDS), also called hydrotreatment or hydrotreating, is a catalytic chemical process widely used to remove sulfur (S) from natural gas and from refined petroleum products, such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils. The purpose of removing the sulfur, and creating products such as ultra-low-sulfur diesel, is to reduce the sulfur dioxide emissions that result from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion.
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 Penex process is a continuous catalytic process used in the refining of crude oil. It isomerizes light naphtha (C5/C6) into higher-octane, branched C5/C6 molecules. It also reduces the concentration of benzene in the gasoline pool. It was first used commercially in 1958. Ideally, the isomerization catalyst converts normal pentane (nC5) to isopentane (iC5) and normal hexane (nC6) to 2,2- and 2,3-dimethylbutane. The thermodynamic equilibrium is more favorable at low temperature.
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.
Petroleum naphtha is an intermediate hydrocarbon liquid stream derived from the refining of crude oil with CAS-no 64742-48-9. It is most usually desulfurized and then catalytically reformed, which rearranges or restructures the hydrocarbon molecules in the naphtha as well as breaking some of the molecules into smaller molecules to produce a high-octane component of gasoline.
In the petroleum refining and petrochemical industries, the initialism BTX refers to mixtures of benzene, toluene, and the three xylene isomers, all of which are aromatic hydrocarbons. The xylene isomers are distinguished by the designations ortho –, meta –, and para – as indicated in the adjacent diagram. If ethylbenzene is included, the mixture is sometimes referred to as BTEX.
An alkylation unit (alky) is one of the conversion processes used in petroleum refineries. It is used to convert isobutane and low-molecular-weight alkenes (primarily a mixture of propene and butene) into alkylate, a high octane gasoline component. The process occurs in the presence of an acid such as sulfuric acid (H2SO4) or hydrofluoric acid (HF) as catalyst. Depending on the acid used, the unit is called a sulfuric acid alkylation unit (SAAU) or hydrofluoric acid alkylation unit (HFAU). In short, the alky produces a high-quality gasoline blending stock by combining two shorter hydrocarbon molecules into one longer chain gasoline-range molecule by mixing isobutane with a light olefin such as propylene or butylene from the refinery's fluid catalytic cracking unit (FCCU) in the presence of an acid catalyst.
PTT Global Chemical, also known as PTTGC, is a petrochemical company that specializes in synthesizing olefins and aromatics. It was founded in 2011 and is a subsidiary of PTT Public Company Limited.
Steam cracking is a petrochemical process in which saturated hydrocarbons are broken down into smaller, often unsaturated, hydrocarbons. It is the principal industrial method for producing the lighter alkenes, including ethene and propene. Steam cracker units are facilities in which a feedstock such as naphtha, liquefied petroleum gas (LPG), ethane, propane or butane is thermally cracked through the use of steam in steam cracking furnaces to produce lighter hydrocarbons. The propane dehydrogenation process may be accomplished through different commercial technologies. The main differences between each of them concerns the catalyst employed, design of the reactor and strategies to achieve higher conversion rates.
{{cite web}}
: CS1 maint: multiple names: authors list (link)