Construction of ruthenium catalysts based on Ce-Al composite supports for hydrogen production from ammonia decomposition: Mechanism exploration via DFT calculations

In this study, Ru catalysts supported on Ce-Al composite carriers were prepared using the precipitation-hydrothermal method, significantly enhancing ammonia decomposition efficiency. The test results show that the Ru/3Ce-Al catalyst, with a Ru loading of only 0.8 wt%, achieves a reaction rate of 14.17 mmol g cat −1 min −1 at 500 °C, and reaches a 95 % conversion rate at 525 °C. No decline in efficiency was observed after 48 h of durability testing, which significantly reduces the usage of Ru. The RuO 2 particle size in the samples was only 2–4 nm. Ce-Al composite increased the specific surface area and pore volume of the catalyst, facilitating the uniform distribution of Ru. Additionally, it increased the number of surface acidic sites and strengthened the metal-support interaction. The unique low redox potential and oxygen vacancies of CeO 2 allowed for faster electron transfer to the Ru surface. DFT calculations revealed that bridge site adsorption was more stable, with the rate-determining step of the ammonia decomposition reaction being the formation of N 2 . Ce-Al composite catalysts enhanced NH 3 adsorption strength and lowered the reaction energy barrier.