Dimerize propylene

The nickel catalyst under the condition for the 1 1 codimerization is not known to dimerize or polymerize ethylene, although a similar catalyst system has been known to dimerize propylene (26, 27) via a w-allyl intermediate. 

Dimersol G A process for dimerizing propylene to a mixture of isohexenes, suitable for blending into high-octane gasoline. The process is operated in the liquid phase with a dissolved homogeneous catalyst. Developed by IFP and first operated at Alma, MI, in 1977. 

Hexall A process for making hexane by dimerizing propylene. The reaction takes place in the liquid phase in a fixed bed of catalyst. Developed by UOP, but not commercialized as of 1992. 

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. 

Until the mid-1970s metal-catalyzed propylene dimerization had practical significance in isoprene manufacture. Goodyear developed a process to dimerize propylene in the presence of tri-n-propylaluminum to yield 2-methyl-1-pentene.16,95,96 This was then isomerized to 2-methyl-2-pentene followed by cracking into isoprene and methane. This and other synthetic pocesses, however, are no longer practiced since they are not competitive with isoprene manufactured by cracking of naphtha or gas oil. 

Figure 2-7 Dimersol G (an organometaUic catalyst) unit (two CSTRs and one tubular reactor in series) to dimerize propylene into isohexanes. InstitutFranfais du Petrble process. [Photo courtesy of Editions Technip (Institut Fran ais du Petrdle).]...

Figure 1. Pilot-plant apparatus for dimerizing propylene...

The following technical aspects of dimeric propylenes obtained with TT-allylnickel halide catalysts should be noted ... 

The Dimersol Process was first operated commercially in 1977. There are now some 20 plants worldwide with capacities up to 5xio tonnes/y, The process dimerizes and co-dimerizes propylene and butene predominantly for the production of h,igh octane gasoline blending components. 

The final sequences we shall consider are combinations of CSTRs and PFRs I series.. Kn industrial example of reactors in series is. shown in the photo in Fi ure 2-9. Thi.s sequence is used to dimerize propylene into isohexanes, e.g.. 

NifOjCRlj-Ci-BulzAlCl-piperidine or morpholine systems (R is undefined) are also known to dimerize propylene. Conversion of propylene is the highest (80-85%) with piperidine as additive [606]. 

A homogeneous catalyst solution made up of Pd(acac)2, PR3, and EiAlCh in 1,2-dichloroethane dimerizes propylene selectively up to 95% linear hexenes, although at a relatively low reaction rate. Replacement of the phosphine by a phosphite increases the rate but considerably lowers the selectivity [625]. The ratio of P/Pd is critical (P/Pd = 2). At P/Pd S 5 no catalytic activity is observed, presumably due to the blocking of free sites. Relatively high ratios of Al/Pd are required, indicating that the catalytic species is formed in an equilibrium reaction. Activity is found for 5 Al/Pd 25 with an optimum around 20. The following structural formula is proposed for the active species, where P is the phosphine ... 

Thorium nitrate, upon treatment with PPh3 in chlorobenzene solvent and subsequent mixing with Et3Al2Cl3, generates the active catalyst, which can dimerize propylene at 150-500 psi and 115—120°C to give the dimerized products (628,6291. 

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