Snapshots of a working catalyst:: possibilities and limitations of in situ spectroscopy in the field of heterogeneous catalysis

Probing events taking place in a heterogeneous catalyst under reaction conditions has attracted a lot of attention in recent years. It requires the development of characterization techniques and the construction of in situ spectroscopic-reaction cells, which allow the identification of reaction intermediates and active sites in a working catalyst. The ultimate goals are the development of quantitative structure/composition-activity/ selectivity relationships and the gathering of fundamental insight in short- and/or long-term deactivation mechanisms of heterogeneous catalysts. The use of in situ infrared, Raman, UV-VIS, electron paramagnetic resonance, nuclear magnetic resonance, X-ray absorption and Mossbauer spectroscopy; the construction of valuable spectroscopic-reaction cells and the possibilities and limitations to monitor real time catalytic events are reviewed. Several case studies describing the use of in situ spectroscopy in catalysis research are discussed.