Classes of Heterogeneous Catalysts

Such organizations continue to the surfaces which can be viewed as the cross-sections of the 3-dimensional arrays along defined planes of cleavage. The 

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Oxide-supported metals constitute one of the most important classes of heterogeneous catalysts, and for this reason they have been investigated by many techniques adsorption isotherms, IR of chemisorbed molecules, electron microscopy, EXAFS, etc. Flowever, the fact that they have been studied by so many methods proves that no one technique is totally satisfactory. 

A new class of heterogeneous catalyst has emerged from the incorporation of mono- and bimetallic nanocolloids in the mesopores of MCM-41 or via the entrapment of pro-prepared colloidal metal in sol-gel materials [170-172], Noble metal nanoparticles containing Mex-MCM-41 were synthesized using surfactant stabilized palladium, iridium, and rhodium nanoparticles in the synthesis gel. The materials were characterized by a number of physical methods, showed that the nanoparticles were present inside the pores of MCM-41. They were found to be active catalysts in the hydrogenation of cyclic olefins such as cyclohexene, cyclooctene, cyclododecene, and... 

In 1953 K. Ziegler and coworkers discovered a class of heterogeneous catalysts that allowed ethylene to be polymerized at low pressures and low temperatures (low-pressure polyethylene=high-density polyethylene=PEHD). 

Arhancet JP, Davis ME, Merola JS, Hanson BE (1989) Hydroformylation by supported aqueous-phase catalysis a new class of heterogeneous catalysts. Nature 339(6224) 454-455... 

During the last several years our research group has been involved in the development of a new class of heterogeneous catalysts organometallics directly deposited on high surface... 

Predictability of activity, selectivity, and stability based on known structures of catalysts can be considered the main aim of the theoretical approaches applied to catalysis. Here, for a particular class of heterogeneous catalysts, namely, acidic zeolites, we present the theoretical approaches that are available to accomplish this goal, which lead to a better understanding of molecular motion within the zeolitic micropores and the reactivity of zeolitic protons. It is not our aim to introduce the methods as such, since introductory treatments on those can be found elsewhere. Rather we focus on their application and use to solve questions on mechanisms and reactivity in zeolites. The discussion is focused on an understanding of the kinetics of zeolite-catalyzed reactions. 

Shape selectivity. Crystalline zeolites form a special class of heterogeneous catalysts. They are oxides, generally combinations of silica and alumina, having open-framework... 

Arhancet, J. P. Davis, M. E. Merola, J. S. Hanson, B. E. Hydroformylation by supported aqueous-phase catalysis a new class of heterogeneous catalysts. Nature (Lonchn) 1989,339(6224), 454-5. Horvath, I. T. Fluorous Biphase Chemistry. Accounts of Chemical Research 1998,31(10), 641-650. 

Despite the fact that DMCs have been used as dyes for hundreds of years or as industrial catalysts for nearly half a century, they remain a relatively unknown class of heterogeneous catalysts. In the field of epoxide polymerization reactions, this class of materials is already well established as the catalyst of choice. Recent publications have however shown that DMCs offer a much wider applicability and that they can catalyze a broad array of organic reactions, undoubtedly guaranteeing the future applications of these materials in other industrial processes. 

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