This work covers the development of a ceria based AuPt catalyst for the selective aerobic oxidation of alkyl ethoxylates to their corresponding carboxylic acids. By optimizing metal loading and the Au to Pt ratio the activity of the catalyst could be increased significantly, while maintaining total selectivity. Although the choice of ceria as a support helped to suppress intermediate metal leaching, the catalyst still showed poor long-term stability in repeated batches. The cause for deactivation could finally be identified by TPR studies as overoxidation. These suspicions were confirmed by a long-term stability study in continuous-mode. It proved to be possible to deactivate the catalyst on purpose by employing unfavourable oxidising reaction conditions, i.e. low substrate concentrations and excess oxygen. By avoiding such unfavourable conditions either in continuousflow mode or in repeated batches, the long-term stability of the catalyst increased tremendously. A substrate screening of various ethoxylates showed that the catalyst was very well-suited to selectively oxidize a wide range of alkyl ethoxylates.

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The oxidation of the fatty-alcohol ethoxylate GENAPOL LA 050 to its corresponding ether carboxylic acid using supported Au catalysts under mild aerobic conditions in aqueous alkaline solution was investigated. Screening of different metal oxide supports and several preparation methods yielded an assortment of highly selective catalysts with varying activities. AEROXIDE ® TiO 2 P25 turned out to be the most suitable support and deposition-precipitation with urea emerged as the best-suited preparation method.Further experiments with this catalyst displayed the dependency of the catalytic activity on reaction parameters such as temperature, pressure and reactant/catalyst ratio. The long-term stability study of this particular catalyst in repeated batches revealed catalyst deactivation by Au particle agglomeration due to intermediate Au leaching under the reaction conditions.

Die Gold‐katalysierte Selektivoxidation von Aldehyden und Alkoholen zu den korrespondierenden Carbonsäuren kann für die Funktionalisierung verschiedener Substanzen auf Basis nachwachsender Rohstoffe, z. B. Kohlenhydrate oder Fettalkoholethoxylate, in Zukunft große Bedeutung erlangen. Bei der Kohlenhydratoxidation weisen Goldkatalysatoren eine sehr hohe Aktivität sowie eine exzellente Selektivität und Langzeitstabilität auf und erlauben somit eine hocheffiziente Herstellung verschiedenster Aldonsäuren. Auch bei der Selektivoxidation von Ethoxylaten zeigen Goldkatalysatoren, dass diese universell, mit guter Aktivität und sehr guter Selektivität zu den entsprechenden Ethercarbonsäuren umgesetzt können.