Octane catalysts higher olefin content

The development of ultrastable Y-zeolite catalyst led to the production of gasoline with higher olefin content and increased octane niunber. However, the need for improved catalysts continued because the zeohte was not sufficiently stable and the motor octane number did not rise as much as the research octane number. As discovered previously with other zeolites in the 1960 s, partial exchange of USY-zeolite with rare earth (REUSY) gave better stability as well as activity and provided more branched hydrocarbons and aromatics. Both motor octane number and gasoline production could thus be increased. 

A solid acid catalyst introduced in 1985 is used in UOP s Hexall process to selectively dimerize propylene at high conversion.24 The Colefin content of the product can reach higher than 90% with an octane number of 95-96. 

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