Catalytic pervaporation membrane reactors for the integrated reaction and separation in condensation reactions

Pervaporation membrane reactors are ideal candidates to enhance conversion in reversible reactions generating water as a by-product. This equilibrium displacement can be enhanced through close integration of reaction and separation by way of catalytic membranes. In this research, catalytic hollow fibre pervaporation membranes for the close integration of reaction and separation will be developed. The research has focused on the development of waterselective hollow fibre silica membranes, the heterogeneous catalysis of esterification reactions and on the modeling of the pervaporation-coupled esterification process in a catalytic membrane reactor. The esterification reaction between acetic acid and butanol has been taken as a model reaction, for which a parametric model study was carried out to provide a fundamental understanding of the catalytic membrane reactor behavior. Catalytic membranes consist of a support coated with a water-selective layer and on top of that a porous catalytic layer. Internal mass transfer limitations at thicker catalytic layers and deficiency of catalyst at thin catalytic layers lead to an optimum catalytic layer thickness. At this optimum catalytic layer thickness, the performance of a catalytic membrane reactor exceeds the performance of an inert membrane reactor due to the close integration of reaction and separation. The exact value of this optimum is a function of the reaction kinetics and the membrane permeability. Subsequently, based on the solution method developed optimized catalytic hollow fibres can be prepared if both the reaction and membrane parameters are known.