Gasoline Blending Stocks: Alkylates

Alkylation, where the olefins are reacted with isobutane to make a very desirable gasoline blending stock. Alkylate is an attractive blending component because it has no aromatics or sulfur, low vapor pressure, low end point, and high research and motor octane ratings,... 

Gasoline Blending Stocks Alkylates — Fire Hazards Flash Point (deg. F) < 0 CC ... 

The principal use of the alkylation process is the production of high octane aviation and motor gasoline blending stocks by the chemical addition of C2, C3, C4, or C5 olefins or mixtures of these olefins to an iso-paraffin, usually isobutane. Alkylation of benzene with olefins to produce styrene, cumene, and detergent alkylate are petrochemical processes. The alkylation reaction can be promoted by concentrated sulfuric acid, hydrofluoric acid, aluminum chloride, or boron fluoride at low temperatures. Thermal alkylation is possible at high temperatures and very high pressures. 

Sulfuric acid alkylation an alkylation process in which olefins (C3, C4, and C5) combine with isobutane in the presence of a catalyst (sulfuric acid) to form branched-chain hydrocarbons used especially in gasoline blending stock. 

The C4 s can be recovered in numerous ways to malce petrochemical feeds. Sometimes everything but the butadiene ends up in an alkylation plant that makes gasoline blend stock. 

The fractionation section of the alkylation plant consists of a deisobutanizer, a debutanizer, and a rerun tower in series, and a depropanizer. The deisobutanizer overhead, which contains about 90% isobutane, recycles to the reactor. The deisobutanizer bottoms stream passes to the debutanizer, which removes normal butane diluent as an overhead stream. The debutanizer bottoms or raw alkylate stream then goes to a rerun tower for removal of the high boiling alkylate bottoms or trimers. The rerun overhead requires no further treatment to be satisfactory as an aviation gasoline blending stock. The depropanizer removes propane diluent from a slip-stream portion of the recycle isobutane stream to prevent propane build-up in the reaction system. 

Pentene alkylation also has the disadvantages of increased catalyst consumption and decreased alkylate quality. A further disadvantage is that pentenes are a satisfactory motor gasoline blending stock and are thus a more expensive alkylation charge stock. For these reasons, commercial alkylation of pentenes is not extensively practiced. 

Alkylation This process converts isobutanc and butylenes produced in the catalytic cracking step into a mixture of dimers known as alkylate. This product is a gasoline blending stock of high octane value. Alkylation catalysts are homogeneous liquid catalysis, either sulfuric or hydrofluoric acids. 

Another method to convert light olefins into gasoline-blending stocks is alkylation. In this... 

Hydrocracked gasoline Alkylate gasoline Relatively olefin-free, low aromatic cracked gasoline blendstock. Composed of C and C8branched hydrocarbons this is a high-octane-number blending stock with MON values ranging from approximately 87 to 95 and RON values from 94 to 100. 

Studies have been made thruout the refining industry in an effort to utilize selected stocks for the production of jet fuels. Basically, this would amount to determining the stability of many stocks, for example, straight run gasolines, distillates, kerosines, alkylate bottoms, and whatever else is available from refinery streams. Those with best heat stability, by laboratory test, could then be blended into jet fuels meeting required... 

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