Supported Ionic Liquid Phase SILP Hydroformylation

Supported Ionic Liquid Phase (SILP) Hydroformylation 

In order to reduce the amount of precious ionic liquids and to overcome their high viscosity, which cause low diffusion coefficients for H2 and CO, the immobilization of ionic liquids hosting the catalyst on solid materials is of interest [107]. Immobilization can be achieved by physisorption, tethering, or covalent anchoring of ionic liquid fragments on a porous material. In the ideal case, a thin film is formed containing the catalyst and ionic liquid. 

---

Rhodium Catalysed Hydroformylation Using Supported Ionic Liquid Phase SILP) Catalysis... 

The term Supported Ionic Liquid Phase (SILP) catalysis has recently been introduced into the literature to describe the heterogenisation of a homogeneous catalyst system by confining an ionic liquid solution of catalytically active complexes on a solid support [68], In comparison to the conventional liquid-liquid biphasic catalysis in organic-ionic liquid mixtures, the concept of SILP-catalysis offers very efficient use of the ionic liquid. Figure 7.10 exemplifies the concept for the Rh-catalysed hydroformylation. 

Figure 7.10. Supported ionic liquid phase (SILP) catalysis exemplified for the Rh-catalysed hydroformylation reaction...

Silica-supported ionic liquid-phase (SILP) catalysis has been developed as an alternative approach to address the problem of product isolation, a methodology well known from aqueous catalysis, and an overview of SILP-hydroformylation reactions in ionic liquids is given in Table 4.4.[631... 

It must be also noted that supported ionic liquid phase (SILP) catalysis can also be successfully combined with supercritical fluids. Cole-Hamilton et al. [127] have reported recently high activity (rates up to 800 h ), stable performances (>40 h) and minimum rhodium leaching (0.5 ppm) in the hydroformylation of 1-octene using a system that involves flowing the substrate, reacting gases and products dissolved in... 

Fig. 5.3-2 Schematic representation of a supported ionic liquid phase (SILP) catalyst exemplified for a typical rhodium hydroformylation catalyst.

I Ls can also be immobilized by impregnation of an inorganic support. This is a direct transposition of the Supported Aqueous-Phase Catalysis (SAPC) concept to ionic liquids (see Section 2.6). Supported Ionic Liquid Phase (SILP) catalysts containing Rh-biphosphine ligands were applied to perform continuous-flow gas-phase hydroformylation of propene in [BMIMJIPFg] or [BMIMJIRSOJ (R=octyl). 

Riisager, A., Wasserscheid, P, Van Hal, R., and Fehrmaim, R. (2003) Continuous fixed-bed gas-phase hydroformylation using supported ionic liquid-phase (SILP) Rh catalysts. /. Catal., 219 (2), 452-455. 

Regelein, D. (2005) Hydroformylation of 1 Octene using Supported Ionic Liquid Phase (SILP) Catalysts Diploma Thesis. FAU Erlangen-Nuremherg. 

Haumann, M., )akuttis, M., and Wasserscheid, S.W.P. (2009) Supported ionic liquid phase (SILP) catalyzed hydroformylation of 1-butene in a gradient-free loop reactor. J. Catal., 263, 321-327. 

Riisager, K.M., Eriksen, P.W., and Fehrmann, R. (2003) Propene and 1-Octene hydroformylation with silica-supported, ionic liquid-phase (SILP) Rh-phosphine catalysts in continuous fixed-bed mode. Catal Lett., 90, 149-153. 

Supported Ionic Liquid Phase (SILP) Materials in Hydroformylation Catalysis... 

In 2005, Riisager and Wasserscheid [109] linked a Rh(Sulfoxantphos) complex via [BMIM] [n-CgHj yOSOg] on a partly dehydroxylated silica support. In the hydroformylation of propene, a large dependence on the nature of the support and especially the P/Rh ratio was found. Fast deactivation took place at a small excess of the ligand. The stability of the supported ionic liquid phase (SILP) catalyst was directly related to the degradation of the catalytically active complex. 

Reiche A, Stemich T., Sandner B., Lobitz P. Fleischer G. (1995). Ion transport in gel electrolytes, Electrochimica Acta, International symposium on polymer electrolytes, vol.40, n°13-14, p>p. 2153-2157, (October 1995), ISSN 0013-4686 Riisager A, Wasserscheid P., Van Hal R. Fehrmann R. (2003). Continuous fixed-bed gas-phase hydroformylation using supported ionic liquid phase (SILP) Rh catalysts. /. Catal, vol.219, n°2, pp.452-455, (October 2003), ISSN 00219517 Robert D., Schneider M., Bom M., Mieloszynski J.L. Paquer D. (19%). Influence of heteroatomic systems on anti-wear and extreme pressure properties of organo-sulfur compounds. C, R. Acad, Set, serie Tib, vol.323, p>p.l27-132, (19%), ISSN 0320-8437 Rogers R.D. Seddon K.R. (2003). Ionic Liquids—Solvents of the Future , Scimee, Vol. 302, n°5646, pp. 792-793 (October 2003), ISSN 0036-8075 Seddon K.R. (1997). Ionic Liquids for Clean Technology, J. Chem. Technol. Biotechnol, vol. 68, n°4, pp.351-356, (April 1997), ISSN 0268-2575... 

Another highly efficient protocol for the hydroformylation consists in the combination of an ionic liquid with a solid support material (Figure 6.1). This process denominated supported ionic liquid phase (SILP) catalysis is a concept that combines the advantages of ionic liquids with those of heterogeneous support materials and allows the use of fixed-bed reactors for continuous reactions. 

SILP hydroformylation catalysts were prepared by dissolving appropriate amounts of Rh(CO)2 (acac) and ligand in dried methanol followed by stirring for 30 min. Afterwards, the ionic liquid was added to the solution. After stirring for another 30 min, the support was added and the solution stirred for 60 min. Finally, the methanol was removed in vacuo and a pale red powder was obtained. The supported ionic liquid-phase catalyst was stored imder argon for further use. 

Table 5.6-3 Evaluation of the hydroformylation reaction ofi-hexene to form n,iso-heptanal using supported ionic liquid phase catalysis (SILP), biphasic catalysis and homogeneous catalysis [88]...

The scope of SILP was extended by investigating charged monophosphine ligands, as well as liquid-phase CF hydroformylation. The latter was demonstrated on 1-octene using the SILP Rh-(NORBOS-Cs3)/ [bmim][PF6]/silica catalyst. The authors recognize that the supported catalyst-phihc phase offers the significant advantage of very efficient ionic liquid use. 

SILP catalysts composed of monophosphines (PPha and TPPTS) dissolved in BMI X (X = Pp6 or BF4) on a l-n-butyl-3-[3-(triethoxysilanyl)propyl]imidazolium-modified silica gel support have been prepared and used in rhodiumhexene hydroformylation [39]. The SILP catalysts were found to have higher activity than analogous biphasic systems however, a significant amount of the metal catalyst leached into the product phase at high conversions (rhodium loss of up to 2.1 mol%), because of the depletion of the ionic liquid phase from the support. Importantly, even at lower conversion, pronounced catalyst deactivation was... 

---