Biphasic catalysis SHOP process

Biphasic catalysis is not a new concept for oligomerization chemistry. On the contrary, the oligomerization of ethylene was the first commercialized example of a biphasic, catalytic reaction. The process is known under the name Shell Higher Olefins Process (SHOP) , and the first patents originate from as early as the late 1%0 s. 

As described in the introductory chapter, biphasic catalysis has been around for a long time, but despite a few notable successes such as the Shell Higher Olefin Process (SHOP) and the Rhone-Poulenc-Ruhrchemie hydroformylation process, very few biphasic processes have made it into the industrial arena. The limitations of the solvents used so far in biphasic (or multiphasic) catalysis appear to be overcome by ionic liquids, and even if the perfect ionic liquid is not yet available, then there seems to be almost no limit to the number of new ionic liquids that can be made. It has been estimated that up to 1018 different ionic liquids may exist[1 2] and with such a vast number to choose from it is essential that understanding increases in order to allow accurate predictions of their properties and functions, opening up the possibility of designer solvents. 

The term biphasic catalysis has established itself only slowly, especially since the first commercial appHcations (by Shell in the SHOP process, [18]) named the process thus only tentatively (and in obviously rarely read patent apphcations). 

Probably the first example of a process employing the biphasic concept is the Shell process for ethylene oligomerization in which the nickel catalyst and the ethylene reactant are dissolved in 1,4-butanediol, while the product, a mixture of linear alpha olefins, is insoluble and separates as a second (upper) liquid phase (see Fig. 7.1). This is the first step in the Shell Higher Olefins Process (SHOP), the largest single feed application of homogeneous catalysis [7]. 

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