Elucidation of the role of support in Rh/perovskite catalysts used in ethanol steam reforming reaction

Abstract

Rh/perovskite catalysts were prepared and evaluated in ethanol steam reforming reaction. The samples were characterized by SBET, XRD, XPS, TPR, TG and SEM techniques. It could be possible to obtain perovskites supports with high purity, stability and suitable specific surface areas. The partial substitution of La with Ca and Ce in a LaAlO3 based perovskite structure was reached and changes in its porosity and surface features were detected. The inclusion of Ca into the structure increased specific surface area of support and Ce inclusion activated oxygen mobility on catalyst surface. The supports influenced the degree of reduction of Rh species at the surface of catalysts. All catalyst showed complete ethanol conversion on 6 h on stream. The best catalytic performance was achieved with Rh/LaAlO3 0.3 % catalyst which presented the highest mean value of H2 product distribution, low production of byproducts (CH4 and CO) and presented an excellent long term experience performance during 24 h on stream. Rh/LaCeAlO3 0.3 % presented the lowest carbon accumulation during 6 h on stream but it suffered deactivation after 14 h on stream. The deactivation was attributed to the partial oxidation of Rh° species to Rh3+ which are less active favoring a reaction pathway that produce carbonaceous deposits.