Systematik bei der Entwicklung von Katalysatoren für Oxidationsreaktionen

Systematic approach to development of catalysts for oxidation reactions . The systematic catalyst development presented here for the example of a typical oxidation reaction shows that a systematic procedure is of value for a purposeful approach, and that statistically based planning and evaluation of experimental results represents an efficient tool. Physicochemical methods of study can provide important support for an understanding of catalytic action, with reaction-engineering studies in various kinds of reactors necessarily playing a central role in catalyst development. Technical and economic assessment of a catalyst under development is already feasible in laboratory experiments and ultimately decides for or against its technical applicability. Understandably, the scale-up of a production procedure developed in the laboratory to industrial quantities may also be beset with other problems which cannot be considered here.     

Katalysatoren für den Umweltschutz

Catalysts for environmental protection. The main emitters of anthropogenic air pollution are internal combustion engines, power plants, and production processes. Components of exhaust gases which are regarded as pollutants are hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO_x), sulfur dioxide (SO₂), and dust. Three main types of catalyst are understood to improve the environment; namely automotive emission control, NO_x abatement and oxidation. To reduce the pollutants HC, CO, and NO_x in automobile exhaust gas, three-way catalysts are currently applied. The reduction of particle emissions in diesel exhaust gas is achieved by diesel filters and oxidation catalysts. Pollutants from power plants are mainly the inorganic components NO_x and SO₂. In the SCR process, NO_x is catalytically reduced to nitrogen and water. The DESONOX process is suited for the simultaneous catalytic abatement of NO_x and SO_x. Exhaust gases from production processes in many areas require after-treatment. Therefore catalyst formulations depend on process parameters and exhaust gas components. This overview presents and explains catalyst types, design, mode of operation, and processes.     

Titanhaltige Molekularsiebe als Katalysatoren für selektive Oxidationsreaktionen mit Wasserstoffperoxid

Titanium Containing Molecular Sieves as Catalysts for Selective Oxidation Reactions with Hydrogen Peroxide Titanium silicalite (TS-1) is known to be a highly-efficient and selective redox molecular sieve that has been found to catalyze a range of synthetically useful oxidation reactions with hydrogen peroxide under mild conditions. Among these reactions which are often influenced also by the shape-selective properties of the Ti-containing molecular sieve are olefin epoxidation, the oxidation of alcohols to carbonyl compounds, aromatic hydroxylations and ammoximation of cyclohexanone to cyclohexanone oxime. A critical review on the present literature on TS-1 catalysts and further Ti-containing molecular sieves is given mainly focused on the questions connected with the identification of the catalytic active titanium species and the mechanism of some of the reactions. Therefore, the procedure of the synthesis of TS-1 as well as the results obtained from the most of the physico-chemical investigations are analyzed. There are no final correlations to realize between the parameters of the synthesis, the results of characterization and the catalytic properties of TS-1.     

Eigenschaften hochtemperaturhydrolytisch hergestellter Kieselsäuren und Metalloxide für Katalysatoren

Catalytic properties of silicic acids and metal oxides prepared hydrolytically at high temperatures . The physical and chemical properties of silicic acids and metal oxides (Al₂O₃ and TiO₂ P25) prepared hydrolytically at high temperatures are described, insofar as they might be of interest to catalyst producers. A highly topical literature survey reveals areas of interest in the fields of research and practical applications. The experimental section deals with the preparation of catalyst supports made of highly dispersed silica gel products. Their characteristics are tabulated.