Title : Role of alkali earth metals in tailoring Ni/CeO2 system for efficient ammonia decomposition
Abstract:
The global energy landscape is undergoing a significant transformation, driven by a growing imperative to shift away from traditional fossil fuels. Hydrogen, as an emerging clean energy source, confronts various technical challenges in storage and transportation, notably high costs and operational complexity. With a hydrogen content of up to 17.6wt%, ammonia is recognized as an exceptionally promising hydrogen storage medium. The development of low-temperature, non- precious metal catalysts for ammonia decomposition holds significant promise for advancing the green hydrogen industry. Here, we prepared Nickle catalyst supported on CeO2 support and investigate the influence of alkali earth metal as a promoter on this system for ammonia decomposition. A nominal 10 wt% of Ni loading and 2wt% promoter (X: Mg,Ca,Sr,Ba)) (10wt%Ni- 2wt%promoter/CeO2) was maintained in all catalysts. The catalytic ammonia decomposition performance studied in the temperature range 300–600 °C. The catalyst 10Ni-2Ba/CeO2 (10wt% Ni C 2wt%Ba on CeO2) showed the highest activity among the all-other catalysts and the sequential order of exhibited NH3 conversion as follows: 10Ni-2Mg/CeO2< 10Ni-2Ca/CeO2< 10Ni/CeO2 <10Ni-2Sr/CeO2 ≤ 10Ni-2Ba/CeO2. The synthesized catalysts characterized by BET, XRD, TPR, and CO2-TPD techniques. The results showed that Mg and Ca promoter is not helping to Ni/CeO2 system whereas Sr and Ba is promoting the catalyst performance. The metal reducibility changed with addition of promoters observed to Ni/CeO2 system. The lowest nickel reducibility observed in Mg promoted catalyst and reduction temperature slightly shifted to lower side from Ca to Ba. The moderate basicity of 10Ni-2Ba/CeO2 catalysts facilitates the re combinative desorption of surface N atoms which help in enriching the ammonia decomposition. The interaction between BaCCeO2 is beneficial to electron conductivity that promotes the catalytic activity of 10Ni-2Ba/CeO2.
Keywords: H2 production, Alkali earth metals, Ammonia decomposition
