Top Organomet Chem (2005) 16: 37–68 DOI 10.1007/b138073  Springer-Verlag Berlin Heidelberg 2005 Published online: 14 September 2005 Single Site Catalyst for Partial Oxidation Reaction: TS-1 Case Study S. Bordiga (✉) · A. Damin · F. Bonino · C. Lamberti Department of Inorganic, Physical and Materials Chemistry and NIS Centre of Excellence, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy silvia.bordiga@unito.it 1 Introduction ................................... 38 2 Oxidation Reactions Catalyzed by TS-1 .................... 40 3 Investigation of the Bare TS-1: Anhydrous Catalyst ............. 42 3.1 XRD ....................................... 43 3.2 UV-Vis ...................................... 44 3.3 XANES ...................................... 45 3.4 EXAFS ...................................... 45 3.5 IR ......................................... 45 3.6 Raman ...................................... 46 3.7 Resonant Raman ................................. 46 3.8 The Defective Nature of TS-1 Material: Speculative Model of Framework Sites ..................... 48 4 TS-1 in Interaction with Ligand Molecules .................. 50 4.1 Interaction with Water and Ammonia ..................... 50 4.1.1 UV-Vis ...................................... 50 4.1.2 XANES and EXAFS ............................... 51 4.1.3 IR ......................................... 52 4.1.4 Raman and Resonant Raman .......................... 52 4.1.5 Adsorption Microcalorimetry ......................... 54 4.2 Interaction With Other Molecules ....................... 54 5 TS-1 Interaction With H 2 O/H 2 O 2 Solutions ................. 55 5.1 General Overview ................................ 55 5.2 New Advances from Resonant Raman Spectroscopy ............. 58 5.3 Equilibria between Peroxo and Hydroperoxo species in the TS-1/H 2 O 2 /H 2 O System: In Situ UV-Vis DRS and High Resolution XANES Highlights .................... 61 References ....................................... 65 Abstract We briefly underline the relevance of TS-1 catalyst for industrial applications in mild oxidation reactions using hydrogen peroxide as oxidant and review the experimental works employed over last two decades for understanding the structure of the Ti centers in the bare TS-1 material. After an animated and controversial debate that has lasted in the literature until 1994, several works (reviewed here in depth) have definitively assessed that Ti atoms occupy framework positions substituting a Si atom and forming tetrahedral