Vapour phase hydrogenation of cinnamaldehyde using cobalt supported inside and outside hollow carbon spheres

Abstract

The hydrogenation of cinnamaldehyde is usually performed in the liquid phase in batch mode. In this study, a vapour phase flow system has been used to evaluate the use of cobalt catalysts supported inside and outside hollow carbon spheres (HCSs). The influence of temperature, hydrogen flow rate and catalyst mass on the hydrogenation reaction was investigated. The catalysts generally showed modest conversion to the required products, hydrocinnamaldehyde, 3-phenyl propanol, cinnamyl alcohol together with formation of various decomposition products. The data revealed that the Co@HCS showed better conversion and product selectivity compared to the Co/HCS. The catalysts with smaller particle sizes (ca. 6 nm) were more efficient than big particles (30 – 40 nm). An increase in reaction temperature (200 – 300°C) resulted in a lower cinnamaldehyde conversion and a poor product selectivity. TPR studies revealed that the Co@HCSs had a stronger metal-support interaction than the Co/HCSs catalysts. Catalyst recycling studies revealed that only the Co/HCSs could be regenerated (4 cycles) and post reaction analysis of the catalysts revealed that this was due to HCS pore blockage and not Co sintering.