Heterogeneous catalyst metal catalysts

The metal catalyzed production of polyolefins such as high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and polypropylene (PP) has grown into an enormous industry. Heterogeneous transition metal catalysts are used for the vast majority of PE and all of the PP production. These catalysts fall generally within two broad classes. Most commercial PP is isotactic and is produced with a catalyst based on a combination of titanium chloride and alkylaluminum chlorides. HDPE and LLDPE are produced with either a titanium catalyst or one based on chromium supported on silica. Most commercial titanium-based PE catalysts are supported on MgCl2. 

Studies on heterogeneous Pd metal catalysts for the arylation of alkenes with aryl halides (the Mirozoki-Heck reaction often reported as Heck reaction) [28] continue to... 

Substituting divalent or trivalent elements for the A1 in the framework has been successfully carried out by several groups yielding novel heterogeneous catalysts (metal-substituted ALPOS, MALPOs Thomas et al 2001) for hydrocarbon oxidation and liquid phase oxidation. MALPO catalysts can be complementary to metal-doped silicalite catalysts. Particularly interesting compounds are MALPOs in which a divalent metal (Me) substitutes for the framework Al +, for example MALPO-36 (where M = Mg, Mn, Zn, Co) and MALPO-34 (M = Mg, Mn, Co etc). 

A wide range of catalysts have been reported for dehydrocoupling of OH-containing compounds with silanes. These include acids and bases and both homogeneous and heterogeneous transition-metal catalysts. Such reactions can be useful in organic synthesis (protection of OH groups), in... 

Chiral, insolubilized, catalytically active, transition metal complexes that incorporate DIOP moieties have also been developed by the Paris group (34). Insolubilized complexes exhibit some features of both homogeneous and heterogeneous catalysts. The catalyst can be more easily recovered during product work-up, and greater air stability is observed. In addition, although solvent... 

F. Fischer and H. Tropsch, who first described the conversion of synthesis gas into hydrocarbons and oxygen-containing compounds ( oxygenates ) over heterogeneous transition metal catalysts such as iron/zinc oxide. This reaction was developed into a process for the conversion of coal into gasoline. At present such a process is economically feasible only where coal is plentiful and cheap while access to oil products is limited. Currently only South Africa operates plants using the Fischer-Tropsch process. 

T. Bugi, R. Wirz, and A. Baiker, In Situ Attenuated Total Reflection Infrared Spectroscopy A Sensitive Tool for the Investigation of Reduction-Oxidation Processes on Heterogeneous Pd Metal Catalysts, J. Phys. Chem. B 107, 6774-6781 (2003). 

The high miscibility with H2, the smaller number of phase boundaries (SCF/catalyst vs gas/liquid/catalyst), and the high diffusion rates were recognized relatively early as potentially useful properties of SCFs in hydrogenation reactions using heterogeneous noble metal catalysts. A substantial amount of research in this field has been and still is being carried out in industrial laboratories or in cooperation with the chemical industry. Therefore, the information in the published literature reflects only a limited fraction of the most recent developments. 

Keywords. 3-Functionalized ketones, a-Keto acid derivatives. Cinchona modified Pt catalysts. Chiral imprints. Chiral metal surfaces. Chiral polymers. Cyanohydrin formation. Cyclic Dipeptides, Epoxidation catalysts. Heterogeneous catalysts. Hydrogenation catalysts. Modified metal oxides. Polypeptides, Tartrate-modified Nickel catalysts... 

Rhenium sulfides are effective catalysts for hydrogenation of organic substances and they have the advantage over heterogeneous platinum metal catalysts in that they are not poisoned by sulfur compounds.811 An inorganic reduction that they catalyze is that of NO to N20 at 100°.8b... 

Chapter 7 contains most of the important data on practical enantioselective processes catalyzed by both heterogeneous enantioselective metal catalysts and by homogeneous metal-complex catalysts. 

There are of course also parallels between homogeneous and heterogeneous transition metal catalysts. Many reaction mechanisms of homogeneous and heterogeneous catalysts exhibit similarities with regard to the intermediates and the product distribution. 

Compare the key activation steps in the hydrogenation of aUcenes with homogeneous and heterogeneous transition metal catalysts. What are the names of these steps ... 

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