Ionic Liquids and Catalysis: the IFP Biphasic Difasol Process

Optimal exploitation of raw materials, energy saving, and environmental friendliness take nowadays a major place in the development of catalytic processes. This implies better use of raw materials, lower formation of side products and, if possible, simplified separation workup steps. In this economical and environmental context, one most successful approach to bridge the gap between homogeneous and heterogeneous catalysis is multiphasic catalysis. In its simplest version, the catalyst is dissolved in one phase (generally a polar phase) while the products and the substrates mainly remain in the second one. The catalyst can be separated by simple settling and recycled under mild conditions. Ionic liquids have recently emerged as a new class of solvents, offering large opportunities of developments for biphasic (multiphasic) catalysis. In this chapter, the Ni-catalyzed olefin oligomerization is described. Starting from the original industrial homogeneous Dimersol process, the emergence of the biphasic Difasol system using ionic liquids as the catalyst solvent will be detailed. This biphasic process was designed and developed with the aim of reducing catalyst consumption, waste and chemicals, all in an economical feasible manner. Keywords: ionic liquids; biphasic catalysis; oligomerization; olefins; nickel