Carbonylation SILP catalysts

The use of catalytic SILP materials has been reviewed recently [10] covering Friedel-Crafts reactions [33-37], hydroformylations (Rh-catalyzed) [38], hydrogenation (Rh-catalyzed) [39,40], Heck reactions (Pd-catalyzed) [41], and hydroaminations (Rh-, Pd-, and Zn-catalyzed) [42]. Since then, the SILP concept has been extended to additional catalytic reactions and alternative support materials. In this paper we will present results from continuous, fixed-bed carbonylation and hydroformylation reactions using rhodium-based SILP catalysts as reaction examples demonstrating the advantages of the SILP technology for bulk chemical production. 

The SILP catalyst system was applied for water-free gas-phase carbonylation of methanol at two different gas space velocities, using a continuous... 

In SILP carbonylation we have introduced a new methanol carbonylation SILP Monsanto catalyst, which is different from present catalytic alcohol carbonylation technologies, by using an ionic liquid as reaction medium and by offering an efficient use of the dispersed ionic liquid-based rhodium-iodide complex catalyst phase. In perspective the introduced fixed-bed SILP carbonylation process design requires a smaller reactor size than existing technology in order to obtain the same productivity, which makes the SILP carbonylation concept potentially interesting for technical applications. 

Hydroformylation and Carbonylation Reactions Promoted by SILP Catalysts... 

If the transport limitation is significant, the catalysis occurs predominantly near the surface of the ionic liquid, and the [Rh(CO)2l2] dissolved in the bulk is not fully utilized. One attempt to address these issues was to use a supported ionic liquid phase (SILP) catalyst, as reported by Riisager et al. [Ill], In this system, the ionic liquid (l-butyl-3-methylimidazolium iodide) was supported as a thin film on solid silica (the thin film offers little mass-transport resistance) and used in a fixed-bed continuous reactor with gas-phase methanol. Rates were achieved that were comparable to those in Eastman s bubble column carbonylation reactor with gas-phase reactants [109], but using a much smaller amount of ionic liquid. 

The SILP carbonylation catalyst was prepared by one-step impregnation of sihca support using a methanohc solution of the ionic liquid [BMIMjl and the dimer [Rh(CO)2l]2- The use of the dimeric precursor complex allowed formation of the catalyst anion [Rh(CO)2l2] directly during catalyst preparation without formation of contaminating byproducts in the ionic hquid catalyst solution. 

Fig. 6 Methanol conversion and TOFs for product formation using SILP SiOi - [BMIM] [Rh(CO)2l2] - [BMIM]I catalyst in continuous, gas-phase methanol carbonylation (Reaction conditions T=180°C, P = 20bar, Fco = 50 ncm min" F quid (MeOHiMel = 75 25wt%) = 0.69 gh- ) [49]...

Another example of successful SILP gas-phase reaction is the rhodium-catalyzed carbonylation of methanol [37]. The technical importance of this reaction is indicated by the Monsanto process, the dominant industrial process for the production of acetic acid (and methyl acetate), carried out on a large scale as a homogeneous liquid-phase reaction [38]. Using [Rh(CO)2l2] anions as the catalyticaUy active species, Riisager and coworkers have developed a new silica SILP Monsanto-type catalyst system [39] 21, in which the active rhodium catalyst complex is part of the IL itself. The SILP system was prepared by a one-step impregnation of the silica support using a methanoUc solution of the IL [BMIM]I and the dimeric precursor species [Rh(CO)2l]2, as depicted in Scheme 15.5. 

Table 15.2 Methanol carbonylation with SILP [BMIM][Rh(C0)2l2]-[BMIM]l-SI02 catalyst system [37].

Successful application of the SILP concept has also been achieved in continuous gas-phase carbonylation of methanol using a Monsanto-type catalyst system that contains the catalytically active species as the IL anion, impressively demonstrating the high efficiency of the thin IL catalyst phase. 

Supported ionic liquid phase (SILP) methodology combines the advantage of ionic liquids and those of heterogeneous supports [77], Recently, various SILP-Pd catalysts XXVI, based on imidazolium ionic liquids coordinated to Pd and supported on silica gel, have been prepared. These species were active in the double carbonylation of iodobenzene in the presence of secondary amines, yielding a-ketoamides 78 (Scheme 5.56). In general, the SILP-Pd catalysts XXVI showed selectivity toward double carbonylation, except for the case of using bulky amines, where amides 79 were obtained as the main products. Moreover, under the optimal conditions, these catalysts could be recycled up to six times [78]. 

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