Catalysis supports

Aqueous phase catalysis, supported, for green olefin hydroformylation, 12, 855 Aquo complexes, with Ru and Os half-sandwiches,... 

Liquid injection molding, for silicone rubbers, 3, 674—675 Liquid ligands, in metal vapor synthesis, 1, 229 Liquid-phase catalysis, supported, for green olefin hydroformylation, 12, 855 Lithiacarbaboranes, preparation, 3, 114 Lithiation, arene chromium tricarbonyls, 5, 236 Lithium aluminum amides, reactions, 3, 282 Lithium aluminum hydride, for alcohol reductions, 3, 279 Lithium borohydride, in hydroborations, 9, 158 Lithium gallium hydride, in reduction reactions, 9, 738 Lithium indium hydride, in carbonyl reductions, 9, 713—714... 

An interesting alternative that combines the advantages of both classical and quantum mechanics is to use hybrid QM/MM models, first introduced by Arieh Warshel for modeling enzymatic reactions [7]. Here, the chemical species at the active site are treated using high-level (and therefore expensive) QM models, which are coupled to a force field that describes the reaction environment. Hybrid models can thus take into account solvent effects in homogeneous catalysis, support structure and interface effects in heterogeneous catalysis, and enzyme structure effects in biocatalysis. 

In addition to dense monolithic ceramics, porous silicon nitrides are gaining more importance in technological applications [24], Some porous silicon nitrides with high specific surface area have already been applied as catalysis supports, hot gas filters and biomaterials [25], There is an emerging tendency to facilitate silicon nitride as biomaterial, because of specific mechanical properties that are important for medical applications [25], Moreover, in a recent study it was shown that silicon nitride is a non-toxic, biocompatible ceramic which has the ability to propagate human bone cells in vitro [25], Bioglass and silicon nitride composites have already been realized to combine... 

The catalyst support may either be inert or play a role in catalysis. Supports typically have a high internal surface area. Special shapes (e.g., trilobed particles) are often used to maximize the geometric surface area of the catalyst per reactor volume (and thereby increase the reaction rate per unit volume for diffusion-limited reactions) or to minimize pressure drop. Smaller particles may be used instead of shaped catalysts however, the pressure drop increases and compressor costs become an issue. For fixed beds, the catalyst size range is 1 to 5 mm (0.04 to 0.197 in). In reactors where pressure drop is not an issue, such as fluidized and transport reactors, particle diameters can average less than 0.1 mm (0.0039 in). Smaller particles improve fluidization however, they are entrained and have to be recovered. In slurry beds the diameters can be from about 1.0 mm (0.039 in) down to 10 Jim or less. 

Since Haruta s initial report (Sanchez et al., 1997) of the unexpected activity of supported gold catalysts for low-temperature CO oxidation, there has been a resurgence of research and interest in gold-mediated catalysis. Supported gold clusters have since been found to be active in a... 

The studies described here have been performed within the European Research Group "Ab Initio Molecular Dynamics Applied to Catalysis", supported by the Centre National de la Recherche Scientifique (CNRS), the Institut Frangais du Petrole (IFF) and TotalFinaElf. X. R. thanks TotalFinaElf for the support. 

Mesoporous materials with spherical morphology are quite attractive due to the potential applications in macromolecular separation, drug delivery, catalysis support, and template... 

Hj/CO) phase transfer catalysis supported metal complexes, liquid biphasic catalysis C0/H,0... 

New types of mesoporous molecular sieves (their first synthesis opened a new subfield of molecular sieve chemistry) have been prepared over the last ten years by new synthetic approaches, different from those known for zeolites. The variety of the synthetic procedures described and the differences in the textural properties due to different synthetic procedures, as well as to the high temperature treatment, give evidence that mesoporous molecular sieves of different chemical compositions are very interesting materials not only in materials science. They could be important also for the application as heterogeneous catalysis, support for immobilization of homogeneous catalysts, adsorbents or materials for synthesis of new types of inclusion compounds. 

One-stage hydrocracking of vacuum gas oil over NiMo catalysis supported on MCM-41, USY and amorphous silica-alumina (ASA)... 

Catalyzed reaction Homogeneous catalysis Supported catalysis Heterogeneous catalysis... 

Polymer functionalization aims at imparting new properties (e.g. chemical, biophysical, physicochemical or optoelectronic) to materials. Functional polymers have been developed for a wide range of diverse applications. These include organic catalysis (support catalysts), medicine (red-blood-cell substitutes), optoelectronics (conducting polymers, magnetic polymers and polymers for nonlinear optics), biomaterials, paints and varnishes, building materids, photographic materials as weU as lube and fuel additives. While it is not possible to enum ate all of the applications of functional polymers, some representative examples of functional polymers are listed below. 

Earlier in this section we stated that in many respects transition metal catalysis in ionic liquids is better regarded as heterogeneous catalysis on a liquid support than as conventional homogeneous catalysis in an alternative solvent. As in heterogeneous catalysis, support-ionic liquids and can lead to catalyst activation (see Section 5.3.1.2 for more details). Product separation from an ionic catalyst layer is often easy (at least if the products are not too polar and have a significant vapor pressure) as in dassical heterogeneous catalysis. However, mass transfer limitation problems (when the chemical kinetics... 

A.B. Stiles, Catalysis Supports and Supported Catalysts. Butterworth, London 1987... 

In addition to hydrogenation catalysis, supported IL membranes were also studied for their use as oligomerization catalysts. Such membranes were prepared by loading porous polyethersulfone support membranes with chloroaluminate-based ILs with and without a nickel dimerization catalyst [22]. Although both catalyst types converted ethylene with high activity, the nickel-containing membrane exhibited the higher selectivity for butene production. 

Apart from catalysis, supported IL membranes have also been investigated for a variety of separation applications [23], which ranged from the separation of isomeric amines [24] to the enzyme-fadlitated transport of (S)-ibuprofen through a supported liquid membrane [25], The latter study demonstrated the selective separation of the (S)-enantiomer from the racemic mixture (see Figure 3). The concept was that by employing certain enzymes, such as lipase, it would be possible to catalyze the hydrolysis or the esterification ofibuprofen enantioselectively. In this investigation... 

Polyethylacrylate/SiOj Catalysis support, stationary phase for chromatography... 

If supported ILs are used for catalysis (supported ionic liquid phase, SILP solid catalyst with ionic liquid layer, SCILL), the layer thickness (Sj ) is small, mostly only a few layers or even only a monolayer, that is, 1 run. For a conservative estimation of the characteristic time of diffusion, we assume a value of 10 run, which is in the order of magnitude of the diameter of a mesopore. The characteristic... 

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