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Petroleum naphtha is an intermediate hydrocarbon liquid stream derived from the refining of crude oil. It is most usually desulfurized and then catalytically reformed, which re-arranges or re-structures 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 (or petrol). There are hundreds of different petroleum crude oil sources worldwide and each crude oil has its own unique composition or assay. There are also hundreds of petroleum refineries worldwide and each of them is designed to process either a specific crude oil or specific types of crude oils. Naphtha is a general term as each refinery produces its own naphthas with their own unique initial and final boiling points and other physical and compositional characteristics. Naphthas may also be produced from other material such as coal tar, shale deposits, tar sands and the destructive distillation of wood.〔(Exploiting the Benefits of Fischer-Tropsch Technology ) (Sasol’s integrated business model)〕〔Beychok, M.R., ''Process and environmental technology for producing SNG and liquid fuels'', U.S. EPA report EPA-660/2-75-011, May 1975〕 ==The major source of petroleum naphtha in a petroleum refinery== The first unit process in a petroleum refinery is the crude oil distillation unit. The overhead liquid distillate from that unit is called ''virgin'' or ''straight-run'' naphtha and that distillate is the largest source of naphtha in most petroleum refineries. The naphtha is a mixture of many different hydrocarbon compounds. It has an initial boiling point (IBP) of about 35 °C and a final boiling point (FBP) of about 200 °C, and it contains paraffin, naphthene (cyclic paraffins) and aromatic hydrocarbons ranging from those containing 4 carbon atoms to those containing about 10 or 11 carbon atoms. The virgin naphtha is often further distilled into two streams:〔(Fuel Chemistry ) (scroll down to "What is naphtha")〕 * a virgin ''light'' naphtha with an IBP of about 30 °C and a FBP of about 145 °C containing most (but not all) of the hydrocarbons with 6 or less carbon atoms * a virgin ''heavy'' naphtha containing most (but not all) of the hydrocarbons with more than 6 carbon atoms. The heavy naphtha has an IBP of about 140 °C and a FBP of about 205 °C. It is the virgin heavy naphtha that is usually processed in a catalytic reformer because the light naphtha has molecules with 6 or less carbon atoms which, when reformed, tend to crack into butane and lower molecular weight hydrocarbons which are not useful as high-octane gasoline blending components. Also, the molecules with 6 carbon atoms tend to form aromatics which is undesirable because governmental environmental regulations in a number of countries limit the amount of aromatics (most particularly benzene) that gasoline may contain.〔(Canadian regulations on benzene in gasoline )〕〔(Briefing on Benzene in Petrol ) From website of United Kingdom Petroleum Industry Association (UKPIA)〕〔(USA regulations on benzene in gasoline )〕 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「Petroleum naphtha」の詳細全文を読む スポンサード リンク
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