Ethanol steam reforming over Pt/Al2O3 and Rh/Al2O3 catalysts: the effect of impurities on selectivity and catalyst deactivation

摘要

Bioethanol contains different types of organic impurities which can have a significant influence on the catalytic performance during steam reforming of bioethanol. Different C3 functional group impurities were added individually to the pure ethanol to investigate the influence of different functional groups on the ethanol steam reforming reaction over 0.2% Pt/Al2O3 and 0.2% Rh/Al2O3 catalysts at 773 K. It was established that the catalytic behaviour of both of the catalysts is significantly influenced by the different impurities. The addition of 1 mol% C3 alcohols (1-propanol and isopropyl alcohol) decreased the conversion of ethanol and increased the rate of catalyst deactivation. This deactivation of the catalyst in the presence of C3 alcohols was attributed to high olefin formation and incomplete decomposition of the C3 alcohols, which deposited over the catalysts as coke. Propanal, propylamine and acetone addition to the water/ethanol mixture resulted in rapid metal deactivation and a loss of steam reforming activity over the Pt/alumina although ethanol decomposition continued. In contrast the Rh/alumina did not lose all steam reforming activity when acetone and propylamine were added as impurities. On both the catalysts alcoholic impurities produced a large number of carbon nanotubes (CNTs).