Recent progress in diffuse reflectance spectroscopy of supported metal oxide catalysts

Diffuse reflectance spectroscopy is a suitable technique for studying heter ogeneous catalysts, as both d-d and charge transfer transitions of supporte d transition metal ions can be probed. Within the past several years, new d evelopments have resulted in a more detailed understanding of the surface c hemistry of supported metal oxide catalysts. In this review, the fundamenta l advances of the use of diffuse reflectance spectroscopy in the field of h eterogeneous catalysis will be discussed. It will be shown that (1) oxidati on states can be spectroscopically quantified in well-defined conditions; ( 2) chemometrical techniques are crucial for an unbiased analysis of the spe ctra; (3) in situ spectroscopy, in combination with experimental design and on line catalytic measurements, allows the development of relevant structu re-activity relationships, and (4) the reduction kinetics of supported meta l oxides can be evaluated. (C) 1999 Elsevier Science B.V. All rights reserv ed.