Gasoline motor

The majority of xylenes, which are mostly produced by catalytic reforming or petroleum fractions, ate used in motor gasoline (see Gasoline and other MOTORFUELs). The majority of the xylenes that are recovered for petrochemicals use are used to produce PX and OX. PX is the most important commercial isomer. Almost all of the PX is converted to terephthaUc acid and dimethylterephthalate, and then to poly(ethylene terephthalate) for ultimate use in fibers, films, and resins. 

Benzene is stiU used extensively as a gasoline component iu Europe and many countries do not limit the benzene content (134). Exceptions are Austria, Norway, Sweden, and Switzerland, which set the maximum at 5.0 vol % (134). Over 90% of European motor gasolines are below the 5.0 vol % limit set by these countries. It is likely that benzene content of European gasoline will be further reduced iu the future. 

C. L. Dickson and P. W. Woodward, Motor Gasolines, Winter 1988—1989, National Institute for Petroleum and Energy Research, BardesviUe, OHa.,... 

Virgin Naphtha Catalytic Reforming (Powerfortning) This technique is used for the production of high octane motor gasoline, or as a source of aromatic compounds. 

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. 

The fourth basic category is blending of the finished cuts into commercially saleable products such as motor gasoline, kerosene, lubricating oils, and bunker fuel oil, according to their specifications. 

To obtain light ends conversion, alkylation and polymerization are used to increase the relative amounts of liquid fuel products manufactured. Alkylation converts olefins, (propylene, butylenes, amylenes, etc.), into high octane gasoline by reacting them with isobutane. Polymerization involves reaction of propylene and/or butylenes to produce an unsamrated hydrocarbon mixture in the motor gasoline boiling range. 

Seasonal chances in gasoline sales and heating oil sales compel some modifications to be made in conversion level. Therefore, the conversion pattern of a given catalytic cracking unit can vary from season to season. In summer operations, for instance, higher yields of motor gasoline are desired, both from direct production of 5/430° FVT catalytic naphtha and also from conversion of butylenes and isobutane to alkylate. 

When high purity isobutylene is not required, the acid extract from the rich stage may be heated for a few minutes to 250-300°F, and then quickly cooled. Under these conditions the isobutylene dimerizes to form largely 2,4,4, trimethyl pentene-1. This is known as the dimer process and may be used to concentrate i-butenes for dehydrogenation feed, the isobutylene dimer being added to the motor gasoline pool. Trimers, as well as codimers with normal butenes are also produced. 

Most of the propylene polymerized by this process is used in motor gasoline ("Polymer Gasoline"). However, an appreciable portion of the C7, C, and C,2 olefins find use as feedstocks for production of Oxo alcohols. 

Azrto-balm,/. motor highway, -benzin, n. motor gasoline, motor spirit. 

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