24: Operando Techniques
Published:11 May 2017
M. Bauer, U. Bentrup, J. B. Priebe, and A. Brückner, in Contemporary Catalysis: Science, Technology, and Applications, ed. P. C. J. Kamer, D. Vogt, and J. Thybaut, The Royal Society of Chemistry, 2017, pp. 549-588.
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Operando spectroscopic techniques are inevitable tools for deriving relevant relations between structure and performance of catalysts in a reaction as a basis for rational catalyst design. To ensure that the catalysts under study are indeed analyzed in their active working state, the spectroscopic cells must be connected to some kind of on-line product analysis for providing simultaneously data on conversion, selectivity, as well as spectroscopic data. This chapter provides an overview of the most common methods applicable in true operando mode with flowing reactants, at elevated temperatures and a total pressure of p ≥ 1 bar, including X-ray diffraction (XRD), absorption (XAS) and emission methods (XES), vibrational (FTIR and Raman) and electronic spectroscopy (UV-vis), as well as magnetic resonance techniques (NMR, EPR). For each technique, the basic principles, opportunities and limitations of the method are mentioned first, followed by a presentation of typical experimental setups and some instructive application examples from heterogeneous catalysis. The latter are described in more detail; however, application opportunities in homogeneous catalysis are also mentioned. At the end of this chapter, some ideas on future trends are put forward.