Homogene oder heterogene Katalyse? Simultane Verwendung von basischen und sauren Zeolithen in der flüssigen Phase bei der Umesterung und Veresterung

Base catalyzed transesterification of triglycerides with methanol was studied in liquid phase on a K-LSX zeolite. The presence of free fatty acid results in its deactivation. Their esterification was catalyzed by an acidic H-Y zeolite. Surprisingly, in case of mixing of both catalysts, no catalytic activity was observed. Consequently, both reactions should proceed homogeneously because the formation of the intermediate methylat ion is suppressed. This could be explained in term of a fast ion exchange between the K⁺ ions of K-LSX and the H⁺ ions of Y-zeolite. On the other hand, the observed transport limitation indicates on a heterogeneously catalyzed reaction. Therefore, in case of even non-aqueous liquid phase reactions, a contribution of a homogeneous reaction path must be considered.     

Polytrope Kinetikmessung zur Bewertung von Ionenaustauscherharzen für die Veresterung von Acrylsäure mit n‐Butanol

A catalyst screening for the esterification of acrylic acid with n‐butanol is presented. The kinetics was investigated in the temperature range of 70 – 100 °C and the selectivity was determined. The kinetic data fitted well with the Langmuir‐Hinshelwood‐Hougen‐Watson approach. The model was applied for the design of a reactive distillation column. Due to the similar fluid dynamics and the fast data generation a temperature scanning plug flow reactor was used.     

Durchführung von chemischen Reaktionen im Mikrowellenfeld

Feasibility of Chemical Reactions in Microwave Field The article presents a view on the present knowledge of the influence of microwaves on reactions, material‐, and heat transfer. The heating behavior of representative test reactions and material systems in a microwave field is compared to that under thermal energy. Common features and differences between the convective and dielectrical irradiation methods are discussed using the yield, selectivity, and optical purity of the products as main criteria. The energy absorption of substances and substance mixtures in dependence of the input energy and substance quantity is discussed in view of recent problems with the scaling‐up of microwave‐supported reactions.     

Scale‐up und detaillierte Prozessanalyse eines Membranreaktors am Beispiel einer heterogen katalysierten Veresterung

The combination between reaction and pervaporation has been investigated using the example of a heterogeneous catalysed esterification reaction. The process model parameters have been determined based on experimental investigations and a scale‐up has been performed to the pilot scale. A detailed process analysis leads to optimal operating as well as structural variables and two separation sequences have been suggested.