New catalytic materials

A condensation between SnCl4 and [H2Wi204o] ion in hquid phase gave a mixed hydroxide of Sn and W (Sn/W = 2). Calcination of the mixed hydroxide at 1027 K afforded an Sn-W mixed oxide, which acted as a reusable heterogeneous acid catalyst for the cyclization of (R)-citroneLlal, Diels-Alder reactions. 

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The potential for the use of catalysis in support of sustainability is enormous [102, 103]. New heterogeneous and homogeneous catalysts for improved reaction selectivity, and catalyst activity and stabihty, are needed, for example, new catalytic materials with new carbon modifications for nanotubes, new polymers. 

New materials are also finding application in the area of catalysis reiated to the Chemicals industry. For example, microporous [10] materials which have titanium incorporated into the framework structure (e.g. so-calied TS-1) show selective oxidation behaviour with aqueous hydrogen peroxide as oxidizing agent (Figure 5). Two processes based on these new catalytic materials have now been developed and commercialized by ENl. These include the selective oxidation of phenol to catechol and hydroquinone and the ammoxidation of cyclohexanone to e-caproiactam. 

The mechanism of the cocatalytic effect is still a matter of investigation. For most of the systems of interest in electrocatalysis, data for characterization of the surface by means of spectroscopic UHV methods are still missing. Also measurements of changes in the electronic properties of the metal in the presence of adatoms in addition to more intensive application of in situ and on-line methods are desirable for a systematic search of new catalytic materials. 

R. Stobbe, and P. D. Cobden, Applied Catalysis A General, 306, 17 (2006). Discovery of New Catalytic Materials for the Water-Gas Shift Reaction by High Throughput Experimentation. 

Catalysis plays a relevant role in several of these areas of development but, generally, an innovative effort to find new catalytic materials and their integration into advanced reactor technologies is required, e.g., to combine reaction and separation to reduce the overall costs of the process. More specific needs include ... 

The six sections following the overview chapter deal with aspects of selective oxidation that range from theories and concepts to state-of-the-art engineering applications. Several chapters describe the synthesis, characterization, and performance of potentially attractive new catalytic materials. These catalysts range from single crystals with well-defined crystal faces to highly dispersed or amorphous solids. Most of the actual catalytic reactions studied involve the oxidation of hydrocarbons in the range from to C. ... 

The selectivity for citronellal increases up to a value of 81% (at 100% canv.) for a Sn/Rh ratio of 0.12. Above these values, the selectivity far citronellal decreases and the selectivity for geraniol and nerol increases up to 96% (at 100% conv.) for a Sn/Rh ratio of 0.92. Significant variations of activities are simultaneously observed suggesting selective metallic surface poisoning fallowed by enhanced catalytic activity due to a new catalytic material which contains a tin din-butyl fragment. 

In the same publication, a method for the parallelization of TAP experiments was also indicated. It was stated that ...high-throughput transient kinetics carried out in addition to high-throughput catalyst synthesis and testing both accelerate the search for new catalytic materials and bring fundamental insights into reaction mechanisms. ... 

Search for New Catalytic Materials for isomerization of Light Paraffin 1137... 

Search for New Catalytic Materials for Isomerization of Light Paraffin 1143 Tab. 5.2 Composition of the seven best-ranked catalytic materials of the three generations. 

This chapter overviews some strategies that have been developed and applied at the academic level, by presenting a case study on the basis of our own experience the search for new catalytic material and processes adapted to the production and purification of hydrogen for feeding PEM fuel cells. 

This simple example may illustrate that in general the reaction of an organic halide salt [cation]X with an excess of a Lewis-acid MXy can result in new catalytic materials even if other Lewis-acids are applied than AICI3. In contrast, the use of other Lewis-acids to form the ionic liquid of type [cation][MXy+i] + excess MXy (the excess of MXy may be dissolved in the neutral ionic liquid or may form acidic anionic species such as e.g. [M2X2y+i]-) gives access to new combinations of properties (e.g. a liquid, less oxophilic, Lewis-acidic catalyst with defined solubility and acidity properties). In Table 2 other examples of ionic liquids are presented which are formed by the reaction of an organic halide salt with different Lewis-acids. All these systems should be in principle useful acidic catalysts for synthetic organic chemistry even if not all displayed examples have been already discribed in the literature for this application. 

A major aspect of research and development in industrial catalysis is the identification of catalytic materials and reaction conditions that lead to effective catalytic processes. The need for efficient approaches to facilitate the discovery of new solid catalysts is particularly timely in view of the growing need to expand the applications of catalytic technologies beyond the current chemical and petrochemical industries. For example, new catalysts are needed for environmental applications such as treatment of noxious emissions or for pollution prevention. Improved catalysts are needed for new fuel cell applications. The production of high-value specialty chemicals requires the development of new catalytic materials. Furthermore, new catalysts may be combined with biochemical processes for the production of chemicals from renewable resources. The catalysts required for these new applications may be different from those in current use in the chemical and petrochemical industries. 

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