Highly Active Ru/Al2O3 Catalyst for CO2-Free Hydrogen Production via Ammonia Decomposition

Due to the increasing emphasis on environmental protection and energy efficiency, the on-site production of CO2-free hydrogen from ammonia has become a viable option for power generation and clean energy applications. Ammonia (NH3) is a particularly promising hydrogen carrier as it effectively overcomes the challenges associated with hydrogen storage and transportation. However, the thermocatalytic ammonia decomposition reaction (ADR) requires catalysts with high activity and stability.

In this study, we present a synergistic strategy for preparing a highly dispersed Ru/Al2O3 catalyst using an atmosphere-induced method. When synthesized under an oxidizing atmosphere (Ru/Al2O3-O), the RuO2 particles exhibit sizes larger than 10 nm, which subsequently increase to 17.5 nm upon reduction. In contrast, the reducing atmosphere synthesis (Ru/Al2O3-R) results in Ru particles that remain highly dispersed, with sizes below 2 nm.

The resulting K-Ru/Al2O3-R catalyst demonstrates an impressive 97% NH3 conversion efficiency at 450ﾰC and gas hourly space velocities of 18,000 mL/gcat/h. Furthermore, the catalyst exhibits excellent stability, successfully operating in a fixed-bed reactor for 700 hours. To gain further insight into the catalyst's characteristics, advanced techniques such as high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction, and X-ray diffraction patterns were employed to elucidate the morphology and electronic structure of the Ru metal.

In summary, the development of a highly active and stable Ru/Al2O3 catalyst for thermocatalytic ammonia decomposition holds significant value in advancing CO2-free hydrogen production and supporting the implementation of clean energy solutions. This research contributes to the promotion of environmental sustainability and the efficient utilization of resources.