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Alkylation unit, is one of the conversion processes used in the petroleum refineries. It is used to convert isobutane and low-molecular-weight alkenes (primarily a mixture of propene and butene) into an alkylate, a high octane gasoline component. The process occurs in presence of a strong acting acid as catalyst. The acid can be either sulfuric acid or hydrofluoric acid (HF). Depending on the acid used as catalyst the unit takes the name of SAAU (Sulphuric Acid Alkylation Unit) or HFAU (Hydrofluoric Acid Alkylation Unit). Since crude oil generally contains only 10 to 40 percent of hydrocarbon constituents in the gasoline range, refineries use a fluid catalytic cracking unit (FCCU) process to convert high molecular weight hydrocarbons into smaller and more volatile compounds, which are then converted into liquid gasoline-size hydrocarbons. Alkylation processes transform low molecular-weight alkenes and iso-paraffin molecules into larger iso-paraffins with a high octane number. FCCU is a very common unit in a modern oil refinery, but it is not uncommon for a refinery not to have an alkylation unit. Indeed, by 2010 there are some countries in the world without any installed alkylation unit. The product of the unit, the alkylate, is composed of a mixture of high-octane, branched-chain paraffinic hydrocarbons (mostly isoheptane and isooctane). Alkylate is a premium gasoline blending stock because it has exceptional antiknock properties and is clean burning. The octane number of the alkylate depends mainly upon the kind of alkenes used and upon operating conditions. For example, isooctane results from combining butylene with isobutane and has an octane rating of 100 by definition. There are other products in the alkylate effluent, so the octane rating will vary accordingly. == Capacity installed and available technologies == The first alkylation units entered in service in 1940. Since around 1,600,000 barrels per day of capacity have been installed world-wide (capacity installed in 2009),〔(Alkylation capacities world-wide )〕 with an equal share of 800,000 barrels per day for SAAU and HFAU technologies. About 11% of the gasoline pool in American refineries is produced by alkylating isobutane with C3-C5 olefins. According to the Oil & Gas Journal there were 129 U.S. refineries with a capacity of 17,869,189 barrels per day as of 1 January 2011. These refineries had 1,140,077 barrels per day of alkylation capacity. For safety reasons SAAU is the prevalent current technology of choice. Indeed in 1996 around 60% of the installed capacity was based on HF,〔(Solid-acid alkylation process development is at crucial stage )〕 but since then this ratio has been reducing because during the last decade on 10 new alkylation units commissioned, more than 8 of them were HSAU. Two major licensors (sharing a similar share of the market) of the HFAU process are UOP and Conoco Phillips. The main technology used for the HSAU is the STRATCO process licensed by DuPont, followed by the EMRE technology owned by ExxonMobil. In the last ten years, in excess of 85% of the HSAU capacity added worldwide has utilized STRATCO DuPont technology. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Alkylation unit」の詳細全文を読む スポンサード リンク
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