High selectivity to hydrogen on the methane decomposition over Rh/γ-Al2O3–Nd2O3 catalysts

Abstract Methane decomposition was carried out on Rh/γ-Al 2 O 3 and Rh/γ-Al 2 O 3 –Nd 2 O 3 catalysts to produce hydrogen. γ-Al 2 O 3 –Nd 2 O 3 mixed oxides and Rh/γ-Al 2 O 3 –Nd 2 O 3 catalysts were prepared by wet impregnation using Nd(NO 3 ) 3 ·6H 2 O and RhCl 3 ·3H 2 O as precursors. The concentrations for the catalysts were 1.0 wt% for Rh and 1 and 10 wt% for Nd. The reaction was carried out from 400 to 750 °C. All catalysts showed high activity and selectivity at 700 °C, with conversions around 74–79 vol%. The activity per site (TOF) was higher on Rh crystallites size ≥2.1 nm. The Rh catalyst with 10 wt% neodymium concentration was highly selective to hydrogen, 100%. This behavior was explained by the highest interaction between Rh and γ-Al 2 O 3 –Nd 2 O 3 supports. Rh/γ-Al 2 O 3 and Rh/γ-Al 2 O 3 –Nd 2 O 3 with 1 wt% Nd showed selectivities of 89 and 65% at 700 °C respectively and ethane and ethylene products. These products come from the mobility of CHx species on the Rh surface during the reaction. The carbon produced was mainly deposited on the support. Characterization was done by XRD, N 2 adsorption isotherms, HRTEM, EDS-SEM, CO-FTIR, H 2 -TPR, XPS.