Catalysts combinatorial methods

Zech, T, Honicke, D., E ient ond reliable screening of catalysts for microchannel reactors by combinatorial methods, in Proceedings of the 4th International Conference on Microreaction Technology, IMRET 4, pp. 379-389 (5-9 March 2000), AIChE Topical Conf Proc., Atlanta, USA. 

Serra, J.M., Chica, A. and Corma, A. (2003) Development of a low temperature light paraffin isomerization catalysts with improved resistance to water and sulphur by combinatorial methods. Appl. Catal. A Gen., 239, 35. 

Brooks, C.J., Hagemeyer, A., Yaccato, K., Carhart, R., and Herrmann, M. 2005. Combinatorial methods for the discovery of novel catalysts for the WGS reaction. Paper presented at the 19th North American Catalyst Society Meeting, Philadelphia, May 22-27. 

Pigos, J.M., Brooks, C.J., Jacobs, G., and Davis, B.H. 2006. Evidence of enhanced LTS water-gas shift rate with sodium promoted Pt-Zr02-based catalyst discovered by combinatorial methods. Paper presented at the AICHE Annual Meeting, San Fransisco, November 12-17. 

J. M. Pigos, C. J. Brooks, G. Jacobs and B. H. Davis, DRIFTS Studies of platinum-based zirconia catalyst promoted with sodium discovered by combinatorial methods, Prepr. Am. Chem. Soc. Div. Pet. Chem., 2006. 

The focus of this chapter has been on the synthesis of new catalysts by parallel and combinatorial methods. Another aspect important to the development of new catalysts by these methods is the screening of these large libraries. We will not attempt to cover this topic comprehensively but do feel it is necessary to summarize some of the approaches that have been taken. Methods for screening libraries can be divided into both serial and parallel methods. Generally, the serial methods are adaptations of standard methods that allow for rapid individual analysis of each member of a library. Serial approaches for the analysis of libraries can be as simple as use of an auto sampler on a GC or HPLC system or as advanced as laser-induced resonance-enhanced multiphoton ionization of reaction products above the head-space of a catalyst (16) or microprobe sampling MS (63). The determination of en-antioselectivity in catalysis is a particular problem. Reetz et al. (64) reported the use of pseudoenantiomers and MS in the screening of enantioselective catalysis while Finn and co-workers (65) used diastereoselective derivatization followed by MS to measure ee. 

As it can be seen, the investigations of heterogeneous chiral catalysts started in the late 1950s in Japan and has known a worldwide renaissance in the last few years. Because of a multitude of catalysts discovered and developed in the recent years, combinatorial methods have become an important focus of research in asymmetric catalysis [168,169], In the last few years, efficient techniques have been developed for the high throughput parallel screening of chiral catalysts [170-172], However, parallel screening based on product analysis has potential pitfalls, since the e.s. of a... 

Combinatorial methods were also applied in the discovery of new catalysts for the low-temperature oxidation213 and oxidative dehydrogenation of propane.214 A 144-member catalyst library was screened by photothermal deflection spectroscopy and mass spectrometry to find the most active compositions of V-Al-Nb and Cr-Al-Nb oxides for the oxidative dehydrogenation of ethane.215 The ternary combination V(45)-Sn(45)-Mo(10)-O selected by laser-induced fluorescence imaging gave much higher yield than did V205 in the selective oxidation of naphthalene to naphthoquinone.216... 

New catalysts were also discovered by combinatorial methods for epoxidation, specifically, diamine Mn complexes, highly active Fe and salen complexes, and titanium-silsesquioxane.223... 

Mallouk, T. E., Smotkin, E. S., Combinatorial catalyst development methods. In Handbook of Fuel Cells - Fundamentals, Technology and Applications, Vielstich, W., Lamm, A., Gasteiger, H. (eds.), John Wiley Sons, New York, 2003, 2 (Part 3), 334. 

High Throughput Combinatorial Methods for Heterogeneous Catalysts Design and Development... 

Therefore, heterogeneous catalysts present a greater potential for the application of HT and Combinatorial methods, because they involve diverse compositional phases that are usually formed by interfacial reactions during their synthesis, which in turn produce a variety of structural and textural properties, often too vast to prepare and test by traditional methods. In this respect the HT and Combinatorial methods extend the capabilities of the R D cycle, which comprises the synthesis, the characterization of physicochemical properties and the evaluation of catalytic properties. The primary screening HT method gives the possibility of performing a rapid test of hundreds or thousands of compounds using infrared detection methods [27-29]. Alternatively, a detection method called REMPI (Resonance Enhanced Multi Photon Ionization) has been used, which consists of the in situ ionization of reaction products by UV lasers, followed by the detection of the photoions or electrons by spatially addressable microelectrodes placed in the vicinity of the laser beam [30, 31]. 

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