Well-dispersed Rh nanoparticles with high activity for the dry reforming of methane

BETINA FAROLDI, JOHN MÚNERA, JUAN MANUEL FALIVENE, INMACULADA RODRÍGUEZ RAMOS, ÁLVARO GUTIÉRREZ GARCÍA, SILVIA GONZÁLEZ CARRAZÁN, LAURA CORNAGLIA

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 42 p. 16127 - 16138

0360-3199

Rh catalysts with low Rh content were prepared by incipient wetness impregnation using[NH4]3[RhCl6]$3H2O or RhCl3$3H2O as precursor salts, on CaOeSiO2 supports. All solidsshowed a high stability after 48 h on stream for the dry reforming of methane with lowcarbon content, which made them suitable for obtaining ultrapure hydrogen in a membranereactor. The methane conversion and hydrogen recovery were measured increasingthe sweep gas flow rates to rise the driving force for hydrogen permeation. The catalystwith 0.36 wt.% of Rh showed a slight deactivation. However, the Rh(0.6)/CaOeSiO2 solid, inwhich the Rh impregnation was performed using [NH4]3[RhCl6]$3H2O, exhibited an increaseon CH4 conversion of 77% and a hydrogen recovery equal to 84%.Nanoparticles of about 1.4e1.7 nm surface average diameter were detected for thereduced and used solids indicating that Rh is well dispersed and sintering was not producedafter the catalytic tests. Rh particle sizes calculated by CO chemisorption werecoincident with those measured by Transmission Electron Microscopy. Characterization bythis technique and Laser Raman Spectroscopy of the solids used in membrane reactorrevealed the formation of scarce carbon filaments. However, a surface re-oxidation wasdetected in the low loading catalyst used in the membrane reactor suggesting that it is themain cause for the decrease in the activity of the highly dispersed catalyst.