Triolefin process commercial applications

Shawinigan had a need for polymerization-grade ethylene and high-purity butenes. This presented an ideal opportunity for application of the Triolefin Process, The commercial unit was operating at full capacity two weeks after start-up and its performance exceeded that predicted by laboratory and pilot plant studies. Part of the successful operation can be attributed to the very effective elimination of catalyst poisons from the commercial unit. In 1972, operation of the Shawinigan plant was terminated due to a change in economic climate. 

Having traversed some of the key events in the history of olefin metathesis, it is now appropriate to discuss some of the resultant fruits of that early labor in the form of practical applications in organic synthesis. Since the general reaction was bom in the industrial sector, we felt it appropriate to commence with some examples of commercial processes. Among several of the profitable industrial procedures that benefit from olefin metathesis, one of the oldest is the Phillips triolefin process (Scheme 7a) which utilizes a molybdenum-based catalyst system to convert propene (17) into a mixture of 2-butene (18) and ethene (19). These products are then used as monomers for polymer synthesis as well as for general use in petroleum-related applications. The reverse reaction can also be employed to prepare propene for alternative uses. 

It is still unclear how the initiation step in alkene metathesis occurs and how the initial carbene forms. Commercial applications of metathesis include the triolefin process, in which propylene is converted to ethylene and butene, the neohexene process, in which the dimer of isobutylene, Me3CCH=CMe2, is metathesized with ethylene to give Me3CCH=CH2, an intermediate in the manufacture of synthetic musk, and a 1,5-hexadiene synthesis from 1,5-cy-clooctadiene and ethylene. Two other applications, SHOP and ROMP (Shell higher olefins process and ring-opening metathesis polymerization), are discussed in the next section. 

For organic chemists, the term metathesis is used most often to mean alkene or olefin metathesis. This process, which can be catalysed by a range of transition metals, was discovered accidentally in the petrochemical industry. Its first commercial application was in the Phillips triolefin process in which propene was converted to an equilibrium mixture of ethene, 2-butene and the starting propene at 400 °C in the presence of an unknown tungsten species (Scheme 8.51). The process was in use between 1966 and 1972. Interestingly, with changes in feedstock prices and demands, the process is now run in reverse, producing propene from ethene and 2-butene. 

Because olefin metathesis is an equilibrium reaction, the Triolefin Process can be mn in the reverse direction to produce propylene from 2-butene and ethylene. Lyondell licensed the Phillips Triolefin process and opened the first propylene plant based on this technology in 1984, eventually expanding capacity to 450 000 metric tons per year. In 1997, Lummus Technology, who engineered the first two applications under license from Phillips, purchased the technology from Phillips. The metathesis of ethylene and butenes to propylene is now commercialized as Olefins Conversion Technology (OCT )... 

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