Ru/CeO 2 /MgO Catalysts for Enhanced Ammonia Synthesis Efficiency

Ammonia is used as a feedstock in the fertilizer industry and is CO 2 -free hydrogen (H 2 ) and energy carrier. The Haber-Bosch process industrially used for ammonia synthesis is an energy-intensive process. Therefore, developing such efficient catalysts that can effectively synthesize ammonia at mild reaction conditions is highly required. In this study, efficient 1 wt-% Ru/CeO 2 /MgO catalysts were fabricated in various Ce/Mg molar ratios. At first, CeO 2 was impregnated on MgO, and then these prepared CeO 2 /MgO were used as support to fabricate 1 wt-% Ru catalysts. Among all the Ru/CeO 2 /MgO catalysts, the catalysts with Ce/Mg molar ratios 0.1 and 0.3 showed the highest ammonia yields at 400 °C, which was even higher than that attained with pure CeO 2 supported Ru catalyst. The measurement of activation energies and NH 3 , H 2 , and N 2 reaction orders showed that the catalysts with Ce/Mg molar ratios 0.1 and 0.3 had the lowest activation energies and positive values for the H 2 order. Moreover, H 2 -TPR analysis presented a relatively higher value for H 2 consumption at lower temperatures indicating these catalysts with higher efficiency for Ru reduction than others.