No abstract

Ein vielversprechendes Reaktorkonzept zur Prozessintensivierung stellt der Spinning-Disc-Reaktor (SDR) dar. Im Rahmen dieser Arbeit wurde der Reaktor zu einem SDR nach dem Rotor-Stator-Prinzip weiterentwickelt, wobei die rotierende Scheibe von einem zylindrischen Stator umgeben ist. Zum besseren Verständnis der Vorgänge in dem dünnen, stark gescherten Flüssigkeitsfilm wird die Mikrovermischung mithilfe der Villermaux-Dushman-Reaktion untersucht. Darüber hinaus erfolgt eine systematische Untersuchung der Einflussparameter auf die Stoffübergangsvorgänge bei der heterogen katalysierten Glucose-Oxidation. Hierzu wird ein Pt/C-Katalysator auf der Scheibe immobilisiert. Further Development and Characterization of a Rotor-Stator Spinning Disc ReactorThe spinning disc reactor (SDR) is a promising reactor concept for process intensification. For this work, the reactor is modified into a rotor-stator SDR by placing the disc in a cylindrical shroud. The Villermaux-Dushman reaction is applied to investigate the effect of high shear forces on mixing efficiency of liquid flow in the narrow reactor cavity. Subsequently, this allows the methodical examination of mass transfer properties for heterogeneously catalyzed reactions. The glucose oxidation with dissolved oxygen in water is studied as model reaction employing a Pt/C catalyst immobilized on the rotating disc.

Residence-time experiments were used to study the single-phase flow hydrodynamics of a rotor-stator spinning disc reactor. Two reactor setups of different sizes were used to identify the effects of the operating parameters. To precisely determine the central moments of the transfer functions of the reactors, which allow conclusions on the fluid flow profiles in the gap between the moving and nonmoving parts, a deconvolution procedure in the time and frequency domains was established. Residence-time models were compared with regard to their applicability for deconvolution and fitting. The spatial extent of the convectionally back-mixed and the plug-flow regions was quantified with a threshold method. The results were incorporated into an engineering model and compared to literature data.

Process Intensification on Synthesis of Nanoparticles in a Spinning Disc ReactorThe spinning disc reactor with its characteristic fluid dynamics in a thin liquid film on a rotating surface is very potent in gaining access to nanoparticles. To identify the influencing parameters methodically, the micromixing efficiency is determined by the Villermaux-Dushman reaction, a system of competitive parallel reactions. The precipitation of barium sulfate with its fast reaction kinetics and short induction time is used to validate the results. These findings are subsequently applied on the size-selective synthesis of superparamagnetic magnetite nanoparticles via precipitation reaction. Particles size could be controlled in the range between 5 and 10 nm.

The spinning disc reactor (SDR) is used for the size‐selective synthesis and functionalization of nanoscale superparamagnetic iron oxide particles in a single‐step continuous‐flow process. Nanometer‐sized magnetite (Fe3O4) particles are precipitated in a highly sheared thin liquid film on a rapidly rotating disc. A novel liquid‐liquid synthesis is presented whereas control over particle size is reached via adjustable micromixing properties on the disc. The nanoparticles with tailored size, narrow size distribution, and high saturation magnetization can thus meet the special requirements for the use in biotechnological, medical, and catalytic applications. The functionalization of the particles with oleic acid for higher biocompatibility and better dispersibility is accomplished in the SDR in a single step.