Hydroformylation solid surfaces

Anchoring of active catalysts to insoluble materials such as oxides, silicates, and zeolites often reduces the loss of catalyst during the catalytic process (66). The fixation of the active centers can be achieved either by means of their interaction with hydroxyl groups on a solid surface or, alternatively, by means of interactions between the CO ligands of the metal complex and a Lewis acidic center of the surface. Zeolite-supported cobalt catalysts have been reported for hydroformylation reactions (67). 

Immobilization of Homogeneous Hydroformylation Catalysts on Solid Surfaces by Covalent Anchoring... 

An obvious way to combine the advantages of homogeneous and heterogeneous catalysis for optimized hydroformylation catalysis is to covalently anchor the molecular catalyst complex to a solid surface. Such an immobilized catalyst could be used in fixed bed or slurry type reactors and product separation would be as straightforward as for any heterogeneous catalyst. Indeed, this approach has been most widely studied as evidenced by numerous academic papers and patents, reviews, and books (Keim and Driessen-Hoelscher, 1999 and Reek et cd., 2006). 

New concepts are under intense academic and industrial development that allow facile product/catalyst separation (i) immobilization of homogeneous hydroformylation catalysts on solid surfaces by covalent anchoring ... 

These complexes anchored to a solid via a ligand have been tested for a number of reactions including the hydrogenation, hydroformylation, hydrosilylation, isomerization, dimerization, oligomerization, and polymerization of olefins carbonylation of methanol the water gas shift reaction and various oxidation and hydrolysis reactions (see later for some examples). In most cases, the characterization of the supported entities is very limited the surface reactions are often described on the basis of well-known chemistry, confirmed in some cases by spectroscopic data and elemental analysis. 

Abstract The principle of catalytic SILP materials involves surface modification of a porous solid material by an ionic liquid coating. Ionic liquids are salts with melting points below 100 °C, generally characterized by extremely low volatilities. In the examples described in this paper, the ionic liquid coating contains a homogeneously dissolved Rh-complex and constitutes a uniform, thin film, which itself displays the catalytic reactivity in the system. Continuous fixed-bed reactor technology has been applied successfully to demonstrate the feasibility of catalytic SILP materials for propene hydroformylation and methanol carbonylation. 

Due to the heterogeneity of the recently advanced solid-support catalyst for the hydroformylation, direct structural information on catalyst surface has been collected by extended X-ray absorption fine structure (EXAFS). Iwasawa is the first to directly characterize the structure of dimeric rhodium complexes supported on... 

Adsorption of a high-boiling solvent onto a high-surface-area microporous solid yields a supported liquid phase that can be removed from the sohd only by extraction with a second solvent or by distillation at high temperature under vacuum. Under typical reaction conditions, a solid that contains a supported liquid phase looks and behaves as a solid, yet it can dissolve small quantities of a metal complex into the supported phase. One of the first examples of this arrangement was achieved with the immobilization of Rh(CO)(PPh3)2Cl in benzyl butyl phthalate on silica. The supported complex was successfiilly used to effect the gas-phase hydroformylation of propene. 

Another SILP catalyst used under batch conditions employed mesoporous MCM-41 as the solid support. The catalyst was derived from [Rh(CO)2(acac)] and TPPTS (1 5 mol ratio) in the desired IL. The excellent catalytic performance of this SILP catalyst in the hydroformylation of C6-C12 linear alkenes (TOF up to 500 h ) was determined by the large surface area and uniform mesopore structure of MCM-41 and was almost independent of the type of IL used [bmim][BF4], [bmim][PF6] and 1,1,3,3-tetramethylguanidinium lactate. 

Supported aqueous phase catalysts are well known [29, 30]. In these systems, a thin film of water present on the surface of a polar solid support is used to immobilize metal complexes, which are nonvolatile or insoluble in a mobile gaseous or liquid organic phase, respectively [30]. The concept was used successfully, for example, for the hydroformylation of oleyl alcohol over a supported rhodium complex [29]. Here, it was suggested that the reaction occurred at the interface between the aqueous and organic phase. However, the volatility of water necessitated... 

---