Ethanol Steam Reforming by Ni Catalysts for H2 Production: Evaluation of Gd Effect in CeO2 Support

Ni-based catalysts supported on CeO2 doped with Gd were prepared in this work to investigate the role of gadolinium on ethanol conversion, H-2 selectivity, and carbon formation on ethanol steam reforming reaction. For this, catalysts containing 5 wt% of Ni impregnated on supports of ceria modified with different amounts of Gd (1, 5, and 10 wt%) were used. Ex-situ studies of XRPD suggest an increase of the lattice parameters, indicating a solid solution formation between Gd and Ce. Results of TPR showed an increase in metal-support interactions as the content of Gd increased. In situ XRPD studies indicated the formation of a GdNiO ternary phase for the catalysts containing Gd, which is in agreement with the results obtained by XANES. The catalysts were tested at three temperatures: 400 degrees C, 500 degrees C, and 600 degrees C. The conversion and productivity showed dependence with the Gd content and also with the temperature of the reaction. After the catalytic tests, catalysts containing Gd presented filamentous carbon possible due to a change in the reaction pathway. The highest ethanol conversion and H-2 productivity were obtained at 600 degrees C for all catalysts and the best catalyst at this temperature was 5Ni_5GdCeO(2). The promising performance of this catalyst may be associate with the lowest formation of GdNiO ternary phase, among the catalysts containing Gd, which means more Ni-0 active species available to convert ethanol. [GRAPHICS] .

Automated summary

Ni-based catalysts supported on CeO2 doped with Gd were prepared and investigated for ethanol steam reforming reaction. The addition of Gd promoted the formation of solid solution between Gd and Ce, enhanced the metal-support interactions, and induced the formation of GdNiO ternary phase. The catalytic performance was dependent on Gd content and reaction temperature, with the 5Ni_5GdCeO(2) catalyst showing the best performance at 600°C.