Hydrogen production by steam reforming of ethanol over Co3O4/La2O3/CeO2 catalysts synthesized by one-step polymerization method

Abstract

Catalysts composed of Co3O4/La2O3/CeO2 mixtures were synthesized by the one-step polymerization method, with the three precursors of catalysts mixed together in a single step before the polymerization step. The catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (H2-TPR), physisorption of N2 (BET), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), scanning electron microcopy (SEM), and then were tested in the steam reforming of ethanol (SRE, molar ratio=3H2O:1ethanol) at 500°C for 6h. The mixture of the three oxides led to the formation of the Ce(La)Ox solid solution which was characterized by XRD, TPR and XPS. Even the three precursors of the catalysts (La, Ce and Co) were mixed together by the polymerization method, the results indicated that the La2O3 has a very noticeable preference to interact with CeO2 rather than with Co3O4. The catalysts composed of the mixture of the three oxides (Co3O4/La2O3/CeO2) performed better in the catalysis than those catalysts containing only two oxides (Co3O4/CeO2 or Co3O4/La2O3). The increase in concentration of the Ce(La)Ox solid solution in the cobalt catalysts, increased the selectivity to H2 and CO2, decreased the carbon deposition rates during the SRE, and hindered the formation of graphitic carbon. The best performance in the catalysis was reported by the sample containing 12mol% of La2O3 in the mixture (CoCe12La sample), which is promising for SRE.