TiO₂−WO_xCoatings on Aluminum Open Cell Foams as Potential Packing Material for Esterification of Glycolic Acid with Ethanol

Abstract

The application of open cell foams as catalytic supports has been developed in recent years due to their interesting features: large specific surface area (> 300 m 2 m À 3 ), high void fractions (> 0.9) and enhanced internal mass transport. Catalytic foams are highly appealing for the development of structured reactors, especially for multiphase systems. In this paper, catalytic packing material with potential application in structured reactors was developed. Aluminum foams with different macropore sizes were chosen as support for a TiO 2 À WO x catalyst. The main features, geometric and structural, of the foams were established. At optimized conditions a maximum catalyst loading of 234 kg catalyst m À 3 support was obtained, while maintaining significant void fraction (> 0.8). The structured catalyst was successfully implemented in batch reactor for a model reaction, esterification of glycolic acid with ethanol. It was shown that the catalyst does not lose performance during the coating steps and remains active for at least 3 catalytic runs, i. e. 18 h.