Synthesis of heterogeneous catalysts

Table 6.2 Rationalization of the oxidation chemistry applied in the synthesis of heterogeneous catalysts and related functional materials.

Figure 18. The synthesis of heterogeneous catalyst by grafting of Cp Mo(CO)3Cl (3) and [(-)-menthylCp]Mo(CO)3Cl (4) complexes in aluminated mesoporous materials for olefin epoxidation reactions.

Fujdaia. K, L, Tilley, T. D, Design and synthesis of heterogeneous catalysts the thermolytic molecular precursor approach. J, Catal. 2003. 216. 265-275,... 

The application of the molecular imprinting method for the synthesis of heterogeneous catalysts has been investigated examples of molecularly imprinted catalysts are summarized in Table 22.1. In addition to acid-base catalysts with acid and/or... 

In addition, the salicylaldehyde derivative 5 has been reacted with 1,2-diaminoethane to divinylsalenes which were afterwards copolymerized with styrene to cross-linked polymers in which Co(II) was introduced [21]. Also divinyl-substituted Mn(II salen complexes have been successfully copolymerized [22,23]. The aim of this interesting research is the synthesis of heterogeneous catalysts for the asymmetric epoxidation of olefins using chiral Mn(III)-salen complexes [24]. 

Conventional techniques for the synthesis of heterogeneous catalysts often involve the deposition of an inorganic salt precursor onto a porous support via... 

Although the main focus of this chapter is the synthesis of heterogeneous catalysts prepared via dendrimers, it should be noted that both mono- and bimetallic dendrimer nanocomposites have exhibited substantial activity in homogeneous catalytic systems In some cases, the dendrimer can act as a selective barrier,... 

Lee, L, Morales, R., Albiter, M. A., and Zaera, F. 2008. Synthesis of heterogeneous catalysts with well shaped platinum particles to control reaction selectivity. 

Isopropylcyclopentadienyl complexes of lanthanum, neodimium and holmium are used for the synthesis of heterogenic catalysts of the Fisher-Tropsch reaction [118]. For this purpose the silicon oxide containing OH groups on the surface is treated with a THF solution of (i-C3H7C5H4)3Ln. This leads to the fixation of REM ions on the surface of the carrier. Organic groups are removed by heating in vacuum and then the catalyst is doped with palladium. 

K.L. Fudala, T.D. Tilley - Design and Synthesis of Heterogeneous Catalysts the Thermodynamic Molecular Approach, J. Catal. 216, 265,2003. 

Livage, J. (1998) Sol-gel synthesis of heterogeneous catalysts from aqueous solutions. Catal. Today, 41 (1-3), 3-19. 

A low-pressure process has been developed by ICl operating at about 50 atm (700 psi) using a new active copper-based catalyst at 240°C. The synthesis reaction occurs over a bed of heterogeneous catalyst arranged in either sequential adiabatic beds or placed within heat transfer tubes. The reaction is limited by equilibrium, and methanol concentration at the converter s exit rarely exceeds 7%. The converter effluent is cooled to 40°C to condense product methanol, and the unreacted gases are recycled. Crude methanol from the separator contains water and low levels of by-products, which are removed using a two-column distillation system. Figure 5-5 shows the ICl methanol synthesis process. 

Subsequent studies have failed to support the carbide theory, and it is now generally accepted that carbides of the type proposed by Craxford play little or no part in the Fischer-Tropsch synthesis (86, 87). It has, however, recently been suggested, by analogy with the mechanism proposed for the Haber synthesis of ammonia, that carbides formed by dissociative absorption of carbon monoxide would be expected to be readily hydrogenated and could therefore be of importance in Fischer-Tropsch synthesis over heterogeneous catalyst (88). 

There has been considerable recent research interest in the activation of carbon monoxide en route to more complex organic molecules. Among the various reactions that have been investigated and/or newly discovered, the transition metal catalyzed reduction of CO to hydrocarbons (Fischer-Tropsch synthesis) has enjoyed particular attention (l- ). Whereas most of the successful efforts in this area have been directed toward the development of heterogeneous catalysts, there are relatively few homogeneous systems. Among these, two are based on clusters (10,11) and others are stoichiometric in metal (12-17). In this report we detail the synthesis and catalytic chemistry of polystyrene ( ) supported... 

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... 

The chapter Chiral Modification of Catalytic Surfaces [84] in Design of Heterogeneous Catalysts New Approaches based on Synthesis, Characterization and Modelling summarizes the fundamental research related to the chiral hydrogenation of a-ketoesters on cinchona-modified platinum catalysts and that of [3-ketoesters on tartaric acid-modified nickel catalysts. Emphasis is placed on the adsorption of chiral modifiers as well as on the interaction of the modifier and the organic reactant on catalytic surfaces. 

Ma, Z. Zaera, F. In Design of Heterogeneous Catalysts New Approaches based on Synthesis, Characterization and Modelling, Ozkan, U. S. Ed. Wiley-VCH Weinheim, 2008 pp in press. 

An important issue concerning the use of heterogeneous catalysts for biodiesel synthesis is the lack of systematic research exploring the principles of solid catalyst activity for transesterification of TGs and esterification of FFAs with alcohols. For instance, the question about the true catalytic nature of some solid bases, called heterogeneous, remains unanswered. For example, the most active heterogeneous catalysts reported to date is Ba(OH)2. However, due to its... 

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