Homogeneous Catalysis: A Wedding of Theory and Experiment. The Eugene J. Houdry Award Address

Great Britaiin dominated the chemical industry, particularly the dyestuff industyr, during the last half of the nineteenth century. William Henry Perkin, who had a post at the Royal College of Chemistry in London when he was 17, but who was working at the time in his home laboratory, oxidizedaniline sulfate with k₂Cr₂O₇ and obtained the dye aniline purple or mauve. Recognizing its potential, he resigned his academic position and together with his father began commercial manufacture of the dye when he was 19 years old. Perkin retired in 1874 at the age of 36to devote ful time to research. The other important dye stuff at the time was indigo. Under Imperial Britain, India in 1890 produced 5 million pounds of indigo from the woad plant; its selling price was $3/lb. Chemists at Badische Anilin and Soda Fabrik had been trying to synthesize indigo for many years and in 1897, after 18 years of research, the company achieved the first commercial synthesis. The major stumbling block in the process had been the oxidation of naphthalene to phthalic anhydride, and the successful solution of the problem resulted from an accident. A chemist by the name of Sapper accidentally broke a thermometer while he was trying to oxidize naphthalene with sulfuric acid. HgSO₄ turned out ot be a homogeneous catalyst for the reaction, although until this day, to the best of my knowledge, the exact mechanism of the catalysis is not understood. This achievement changed forever the relative position of the chemical industry in Great Britain vis-a-vis Germany, to Germany's advantage. The tremendous economic impact and potential of catalysis was appreciated by the German chemists. In 1901 Ostwald [1] wrote:     

XANES analysis of catalytic systems under reaction conditions

The article gives an overview of the XANES technique contribution to the analysis of multicomponent catalysts. The theoretical basis of the technique, the interpretation of the energy position and intensity of XANES features, and the numerical methods developed to interpret XANES data on catalytic systems are described and discussed in the first part. In the second part, the most recent XANES studies of catalytic samples are reviewed, giving particular attention to the solid state chemistry information extracted under real, in-situ conditions. This concerns structural and redox properties of the systems during preparation stages, activation treatments like reduction, oxychlorination, or sulfidation, and reaction conditions. Additional effort was made to describe the use of XANES to gain insight on electronic properties of catalysts. The influence of all these redox, geometrical and electronic properties on catalytic behavior, particularly as a function of particle size and active metal-support interaction, has also been examined on the light of XANES data.