Catalyst supports copolymers

Poly(styrene—divinylbenzene) copolymers can be used as catalyst supports. Attachment of catalytic groups to the polymer supports can be achieved by... 

Kragl and Dreisbach reported on the asymmetric diethylzinc addition to benzaldehyde using a chiral homogeneous catalyst supported on a soluble polymethacrylate.[55] l, L-Diphenyl-L-prolinol was bound to a copolymer from 2-hydroxyethylmethacrylate and octadecylmethacrylate forming a soluble catalyst with a Mw of 96 000 (Figure 4.39). 

As early as in 1985, supported catalysts were described for the use in a solution process [399]. Bergbreiter et al. used catalyst supports on the basis of divinylbenzene-styrene-copolymers as well as on polyethylene. These authors found that the use of supported catalysts has no influence on the stereospecificity of diene polymerization. 

Poly(ethylene oxide) (PEO) has been employed frequently as a water-soluble catalyst support [9]. Further water-soluble polymers investigated include other linear polymers such as poly(acrylic acid) [10], poly(N-alkylacrylamide)s [11], and copolymers of maleic anhydride and methylvinylether [12], as well as dendritic materials such as poly(ethyleneimin) [10a, c] or PEO derivatives of polyaryl ethers [13]. The term dendritic refers to a highly branched, tree-like structure and includes perfectly branched dendrimers as well as statistically branched, hyperbranched macromolecules. 

An example of a consecutive use of block copolymer micelles as endo- and exo-templates is the preparation of mesoporous silica with embedded Pd-nanoparticles [113]. As a first step Pd-nanoparticles are prepared in the micellar core (see Sect. 4.1). In a lyotropic phase of these micelles they are further employed as exotemplates for the preparation of mesoporous silica (see Sect. 5). After removal of the block copolymer by calcination, nanoparticles within the open mesopore structure are obtained (Fig. 20). This represents a promising way to incorporate catalytically active nanoparticles into mesoporous oxides as stable catalyst supports. 

Catalytic Hydrogenation of Olefins in Supercritical Carbon Dioxide Using Rhodium Catalysts Supported on Fluoroacrylate Copolymers... 

A new SCCO2 soluble Rh catalyst supported on fluoroacrylate copolymers was synthesized. The catalysts were active for hydrogenation of 1-octene and cyclohexene. The optimal Rh to copolymer molar ratio was 3. Using... 

The structures of anionic, triple-nuclear osmium and iron cluster catalysts supported on copolymers of styrene and divinylbenzene were analyzed by means of IR spectroscopy. Their catalytic activity during 1-hexene hydroformylation [250] and C5H5NO2 carbonylation [251] were investigated. It was found that isomerization proceeds simultaneously in the presence conventional catalysts. In the absence of moisture, a triple-nuclear osmium complex could be removed from a polymeric support after reaction. This suggests catalytic activity for this complex, particularly in the fixed state. Furthermore, a definite correlation was found to exist between polynuclearity and selectivity of heptanol formation. For iron, however, the cluster structure altered during the course of the reaction. 

Semicrystalline polyolefin blends were prepared by mixing two different random copolymers of propene with 4-lOC alpha-olefin at a ratio from 1 3-1 1. The first copolymer contained 1-10 wt% of C4 io alpha-olefin (1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene), whereas the second 15 0 wt% of the same comonomer. The mixing was carried out in reactors, polymerizing the monomers in the presence of stereospecific catalysts supports on active magnesium dihalides, in at least two sequential stages. The resulting R-TPOs showed limited... 

Chien and He used a Et(Ind)2ZrCl2 supported catalysts to produce a munber of copolymers. The reactivity ratios were the same as those found for the analogous homogeneous systems. By comparison, Soga and Kaminaka found that the comparative homogeneous reactivity systems varied with the particular support system utilized. In general, alumina supported catalysts produced copolymers with narrow molecular weight ratios. 

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