Steam reforming of ethanol at medium pressure over Ru/Al2O3: effect of temperature and catalyst deactivation

Abstract

In this study a low-loaded 0.2% Ru/alumina catalyst was tested over a range of temperatures (773–873 K) at 20 barg with a 5 : 1 steam to ethanol ratio. Ruthenium was found to produce significant amounts of ethene, although in the steady state hydrogen was always the main product. Significant levels of methane and carbon dioxide were formed at 873 K. Hydrogenation of ethene to ethane was inhibited and an activation energy comparable with low temperature studies was obtained. Liquid products such as acetaldehyde, diethyl ether and acetone were also produced at low levels (<12%). Temperature-programmed oxidation (TPO), Raman spectroscopy, powder XRD, BET and SEM analysis were used to characterise the nature of the coke species for reactions at 773 K, 823 K and 873 K. The TPO results indicate that different types of coke are deposited on the catalyst during ethanol steam reforming (ESR). Carbon nanotubes and filamentous coke were observed on the catalyst after ESR at 873 K. Powder XRD and Raman analysis revealed that the coke deposited on the catalysts was graphitic in nature and the disorder in the graphitic type coke generally increased with in an increase in the reaction temperature.