Tools in Catalysis Research

Catalysis plays an integral role in many chemical reactions, all the way from petrochemistry to pharmaceutical chemistry. Because catalysis covers such a wide area, researchers use a variety of tools. These can be roughly divided into three 

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Kubanek, P., Busch, O., Thomson, S. et al. (2004) Imaging reflection IR spectroscopy as a tool to achieve higher integration for high-throughput experimentation in catalysis research. J. Comb. Chem., 6, 420. 

Mossbauer spectroscopy is a technique that spans many different disciplines. We hope that this has been reflected in the present paper, in which we have discussed catalytic problems in terms of the physical principles that form the basis for Mossbauer spectroscopy. Certainly, this technique has great potential as a tool in catalytic research. However, in order to take full advantage of this potential, strong ties between researchers in catalysis on one hand and physicists and theoretical chemists on the other hand are necessary, and this will undoubtedly lead to further Advances in Catalysis. 

Theoretical Approaches. Computer modeling is an increasingly fruitful tool in catalysis, and several research groups have attempted to rationalize high carbon conversion over zeolites from a theoretical point of view. The main problem to be... 

NMR is firmly established as a research tool in catalysis, and the interested reader is referred to NMR Techniques in Catalysis (5), edited by Bell and Pines and published in 1994, for an overview of the diverse research objectives and approaches in NMR studies of catalytic materials. 

Based on the above made conclusions it becomes clear that high-throughput experimentation has kept the promise of becoming an important additional tool for catalysis research in academia and industry. 

As described above, gas sensors as HTS tools in catalysis have been applied in several reactions due to their small size, easy parallelization and high sensitivity. We expect the importance of gas sensors to increase for HTS in catalysis. Recently, Simon et al. reported the development of gas sensors with a combinatorial approach [35]. Developing tailor-made gas sensors for specific reactions, this technology will become increasingly important for catalysis researchers. 

This chapter outlines the principles of green chemistry, and explains the connection between catalysis and sustainable development. It covers the concepts of environmental impact, atom economy, and life-cycle analysis, with hands-on examples. Then it introduces the reader to heterogeneous catalysis, homogeneous catalysis, and biocatalysis, explaining what catalysis is and why it is important. The last two sections give an overview of the tools used in catalysis research, and a list of recommended books on specialized subjects in catalysis. 

Figure 1.21 Block diagram of the various tools used in catalysis research.

By simulating evolution in vitro it has become possible to isolate artificial ribozymes from synthetic combinatorial RNA libraries [1, 2]. This approach has great potential for many reasons. First, this strategy enables generation of catalysts that accelerate a variety of chemical reactions, e.g. amide bond formation, N-glycosidic bond formation, or Michael reactions. This combinatorial approach is a powerful tool for catalysis research, because neither prior knowledge of structural prerequisites or reaction mechanisms nor laborious trial-and-error syntheses are necessary (also for non-enzymatic reactions, as discussed in Chapter 5.4). The iterative procedure of in-vitro selection enables handling of up to 1016 different compounds... 

In the early seventies, x-ray photoelectron spectroscopy (XPS) emerged as an important tool for characterization of catalysts (1-3). The principle advantages of XPS are that it identifies the elemental composition of the sample surface, and it gives some indication of the chemical state of these elements. The latter capability has been exploited most often in catalysis research. 

We have already mentioned that fundamental studies in catalysis often require the use of single crystals or other model systems. As catalyst characterization in academic research aims to determine the surface composition on the molecular level under the conditions where the catalyst does its work, one can in principle adopt two approaches. The first is to model the catalytic surface, for example with that of a single crystal. By using the appropriate combination of surface science tools, the desired characterization on the atomic scale is certainly possible in favorable cases. However, although one may be able to study the catalytic properties of such samples under realistic conditions (pressures of 1 atm or higher), most of the characterization is necessarily carried out in ultrahigh vacuum, and not under reaction conditions. 

A survey of the literature shows that although very different calorimeters or microcalorimeters have been used for measuring heats of adsorption, most of them were of the adiabatic type, only a few were isothermal, and until recently (14, 15), none were typical heat-flow calorimeters. This results probably from the fact that heat-flow calorimetry was developed more recently than isothermal or adiabatic calorimetry (16, 17). We believe, however, from our experience, that heat-flow calorimeters present, for the measurement of heats of adsorption, qualities and advantages which are not met by other calorimeters. Without entering, at this point, upon a discussion of the respective merits of different adsorption calorimeters, let us indicate briefly that heat-flow calorimeters are particularly adapted to the investigation (1) of slow adsorption or reaction processes, (2) at moderate or high temperatures, and (3) on solids which present a poor thermal diffusivity. Heat-flow calorimetry appears thus to allow the study of adsorption or reaction processes which cannot be studied conveniently with the usual adiabatic or pseudoadiabatic, adsorption calorimeters. In this respect, heat-flow calorimetry should be considered, actually, as a new tool in adsorption and heterogeneous catalysis research. 

Research tools and fundamental understanding New catalyst design for effective integration of bio-, homo- and heterogeneous catalysis New approaches to realize one-pot complex multistep reactions Understanding catalytic processes at the interface in nanocomposites New routes for nano-design of complex catalysis, hybrid catalytic materials and reactive thin films New preparation methods to synthesize tailored catalytic surfaces New theoretical and computational predictive tools for catalysis and catalytic reaction engineering... 

In conclusion, molecularly imprinted polymers and related materials have every potential to become popular tools in analytical chemistry, catalysis, and sensor technology. Obviously this will require further research, especially in the problem areas of MI mentioned above. Nevertheless, the author of this contribution fully expects that in the near future MIP will become real competitors for biological enzymes or antibodies, and thus will have a major impact on the whole area of biotechnology. 

The vibrational spectrum of a molecule adsorbed on a metal surface contains detailed information about the metal-adsorbate bonds, the local orientation of the molecule, and intermolecular interactions within the adsorbate layer. It is this detailed information about the adsorbate layer that makes vibrational spectroscopy and most prominently IR spectroscopy an important tool in heterogeneous catalysis research. 

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