Comprehensive Design of a Gas/Liquid/SolidMembrane-based Polymerisation Reactor

点击翻译按钮获取中文摘要

With the need for more energy-efficient and sustainable processes at simultaneously improved product quality, even established chemical processes have to be reevaluated and newly designed. Although continuous reactors offer a significantly higher heat and mass transfer capacity compared to batch reactors, many processes are still using batch reactors. Especially gas-liquid reactions, which are often limited by heat and mass transfer, could benefit from the continuous operation. Usually, gas-liquid reactions are realized by dispersing gas bubbles in a stirred tank reactor. An agitator breaks the gas bubbles up to increase the interfacial area between the liquid and the gaseous phase. Although common practice, this method has a very low mechanical efficiency and can not create a defined interfacial area. Membrane contactors, on the other side, can create a stable interfacial area between gas and liquid phase combined with a high surface-to-volume ratio. Hence, membrane contactors are promising reactor systems for many gas-liquid reactions.Here, we propose to develop a new continuous membrane based reactor system for gas-liquid reactions. As a first reaction, the emulsion polymerization of vinylidene fluoride, which is fed as gaseous educt, to polyvinylidene fluoride (PVDF), which will form as solid particles in the liquid phase, will be implemented. In addition to energy savings, a continuous polymerization of PVDF would also be accompanied by the use of less harmful surfactants and a reduction of wastewater.Further, the polymerization reaction in the emulsion polymerization of VDF occurs in micelles, formed by surfactants, as the concentration of monomer molecules in the liquid bulk phase is not sufficient for chain propagation reactions. Hence in this project, the detailed mass transfer mechanisms and limitations of a gaseous monomer through a membrane into a liquid phase with micelles will be studied, and methods to overcome such limitations will be developed.