Ru/La2O3 catalyst for ammonia decomposition to hydrogen

Abstract

Ammonia (NH3) 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 La2O3 synthesized via the citric acid complex, KOH-K2CO3 co-precipitation, pyrolysis and urea method were used as supports of Ru-based catalysts by impregnation to investigate NH3 decomposition. We herein prepared all catalysts for the production of COx-free hydrogen from ammonia decomposition at 300–550 °C. Among the prepared formulations, the Ru/La2O3-700-i catalyst, prepared by a successive conversional impregnation method, shows the highest NH3 conversion (90.7%) with the GHSV of 18000 mL/gcat·h at 525 °C, which is significantly superior to the Ru/La2O3-700-p synthesized via a one-step pyrolysis method. Through XRD and TEM studies, we identify a pure La2O3 phase formation that is responsible for the high catalytic activity of Ru/La2O3-700-i for ammonia decomposition. Moreover, the reaction TOF over the Ru/La2O3-700-i catalyst (1537.6 h−1) is higher than that of the Ru/La2O3-700-p catalyst (1364.1 h−1). The activity of Ru/La2O3-700-i catalyst is found to be even further enhanced in the presence of KOH.