High-performance Rh/CeO2 catalysts prepared by l-lysine-assisted deposition precipitation method for steam reforming of toluene

Abstract

Catalytic steam reforming of aromatic hydrocarbons is important for the hydrogen production from jet/diesel fuels and tar elimination during biomass gasification. In this work, a series of Rh/CeO2 catalysts were prepared by different methods, including impregnation, deposition precipitation (DP) and l-lysine assisted DP (LDP) methods and were used for steam reforming of toluene. The Rh/CeO2(LDP-1) catalyst prepared by LDP method with optimal l-lysine addition (nL-lysine/Rh = 1), showed the superior catalytic activity and stability, as well as the excellent resistance to carbon deposition under severe reaction conditions, mainly because the significant enhancement in Rh dispersion, surface Rh0 content and the concentration of surface oxygen vacancy. The highly dispersed Rh particles with great surface Rh0 content enabled the excellent ability for CC and CH bonds scissions. Meanwhile, the high content of oxygen vacancy on the support facilitated H2O activation, providing available reactive oxygen species for reacting with CHx intermediates and eliminating carbon deposition. Furthermore, the mechanism for the steam reforming of toluene based on a dual-site functional catalyst was proposed, wherein CHO group was identified as a key intermediate for CO, CO2 and H2 gaseous products generation. This study shows that l-lysine-assisted deposition precipitation method provides great advantages in preparing highly active and stable metal-based catalysts for steam reforming reactions.