A Short History of Supported Ionic Liquids

The concept of SI L catalyst has been developed quickly in the last decade. Holderich et al. [4] added acidic chloroaluminate ILs to various types of supports, and the catalytic activities of the immobilized ILs were found to be higher than those of the conventional catalysts under the same conditions. Inspired by this work, SIL catalysts have been widely used in the coupling reactions for olefin hydroformylation [5], olefin metathesis [6], Heck reactions [7], and hydroamination [8], and so on. SIL catalytic systems have also been reported for some other reactions, such as water-gas shift reaction [9], dihydroxylation of olefins [10], and hydrogenation [1 Ij. The solid supports used include magnetic NPs [12], mesoporous molecular sieves [13], soluble organic ions [14], noncovalently solid-phase [15], IL-functionalized carbon nanotubes [16], polymer cocktail [17], and so on. 

In addition, immobilization of active metal components on the support materials with the aid of ILs provides the following features (i) stabilization of the metal catalysts on the surface of the supports, (ii) use of small amounts of IL, and (iii) accumulation of metals on support materials to facilitate catalytic reactions. As a result, the heterogenization of catalysts and reagents can offer important advantages in separation and reuse. 

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