Bioethanol as feedstock for chemicals such as acetaldehyde, ethyl acetate and pure hydrogen

摘要

In the present paper, the development of new heterogeneous catalytic processes to produce high commod- ity chemicals of industrial interest such as acetaldehyde, ethyl acetate, and pure hydrogen by bioethanol has been discussed. All the reactions were performed in a conven- tional packed bed tubular reactor and in a wide range of temperature 50-500°C, pressure 1-30 bar, and space time 07F=0.1-100 gh mol-1. The aim of this research is to demonstrate that by varying properly the operative range of residence time and pressure, it is possible to obtain with high selectivity acetaldehyde or ethyl acetate from ethanol in a single reaction step. The performances of a series of commercial copper-based catalysts have been studied in the ethanol dehydrogenation/oxidative reforming reactions. In particular, very promising results have been obtained by using a commercial catalyst of copper/copper chromite con- taining barium chromite as a promoter. In a low range of residence time 0.1-1 gh mol-' and at low pressure, very high performances in terms of ethanol conversion (60 %) and acetaldehyde selectivity (90 %) have been obtained. On the contrary, by operating at high residence time, at a pres- sure higher than 10 bar, and by feeding 25 cm3/min of a mixture of 6 %H2 in N2, a very high selectivity to ethyl acetate (98.9 %) was observed. The examined catalysts were characterized by using ex situ methods such as X-ray pho- toelectron spectroscopy and in situ EXAFS and FTIR with the aim to evaluate their physical properties and to correlate them with the catalysts' performances.