Multiple-atom-site catalysts for highly efficient hydrogen production from ammonia decomposition over Ru/LaxTiyAz (A = O, N)

The efficient ammonia decomposition catalysts are crucial for advancing the application of hydrogen energy produced from ammonia. Herein, La 2 Ti 2 O 7 and LaTiO 2 N are developed as supports for constructing efficient Ru/La 2 Ti 2 O 7 and Ru/LaTiO 2 N ammonia decomposition catalysts. Compared with monoxide supported catalysts such as Ru/La 2 O 3 , Ru/TiO 2 and Ru/SiO 2 , Ru/La 2 Ti 2 O 7 shows higher activity, achieving an NH 3 conversion rate of 66.5% at 450 °C with a fairly low Ru loading amount (about 1.4 wt%). Using Ru/LaTiO 2 N, we achieve an even higher NH 3 conversion rate (76.1%), hydrogen production rate (1556 mmol/(g Ru ·min)), and 140-hour catalytic stability at 450 °C with a GHSV of 30000 mL/(g cat ·h). Various characterizations demonstrate that the presence of Ti n + is conductive to the adsorption of NH 3 , while the presence of La 3+ with its coordinated O 2– endows La 2 Ti 2 O 7 and LaTiO 2 N with robust surface basicity facilitating the recombination and desorption of N*, together assisting the active metal Ru to catalyze ammonia decomposition. This study provides new material options and design insights from the collective contribution of multiple atom sites in a complex multicomponent heterogeneous catalytic system for the development of efficient Ru-based ammonia decomposition catalysts.