Ru/La2O3 catalyst for ammonia decomposition to hydrogen

Abstract Ammonia (NH 3 ) decomposition for hydrogen production is an excellent alternative to clean energy, but there is a need for more efficient and stable catalytic support to meet the increasing demand for mass production and transportation of hydrogen energy. Four kinds of La 2 O 3 synthesized via the citric acid complex, KOH-K 2 CO 3 co-precipitation, pyrolysis and urea method were used as supports of Ru-based catalysts by impregnation to investigate NH 3 decomposition. We herein prepared all catalysts for the production of CO x -free hydrogen from ammonia decomposition at 300–550 °C. Among the prepared formulations, the Ru/La 2 O 3 -700-i catalyst, prepared by a successive conversional impregnation method, shows the highest NH 3 conversion (90.7%) with the GHSV of 18000 mL/g cat ·h at 525 °C, which is significantly superior to the Ru/La 2 O 3 -700-p synthesized via a one-step pyrolysis method. Through XRD and TEM studies, we identify a pure La 2 O 3 phase formation that is responsible for the high catalytic activity of Ru/La 2 O 3 -700-i for ammonia decomposition. Moreover, the reaction TOF over the Ru/La 2 O 3 -700-i catalyst (1537.6 h −1 ) is higher than that of the Ru/La 2 O 3 -700-p catalyst (1364.1 h −1 ). The activity of Ru/La 2 O 3 -700-i catalyst is found to be even further enhanced in the presence of KOH.