Magnesium-promoted Ni/USY catalysts prepared via surfactant-assisted melt infiltration for ammonia decomposition

Abstract

The dispersion of active metal species on the support material of a catalyst is crucial for efficient catalytic re-actions. Surfactant-assisted melt infiltration (SAMI), in which catalytically active components are supported only by heating with a surfactant instead of a solvent, is a straightforward method for synthesizing highly dispersed catalysts. In this study, monometallic 10 wt% Ni catalyst and alkaline-earth-metal (Mg, Ca, Sr, and Ba)-doped Ni catalysts supported on the ultra-stable Y (USY) zeolite are prepared using SAMI for ammonia decomposition. The addition of SpanTM60 during the preparation of the Ni/USY catalyst improved its catalytic performance. Moreover, the Mg-promoted Ni/USY catalyst prepared via SAMI exhibited further enhancement in catalytic activity and stability, demonstrating the synergistic effect of the SpanTM60 surfactant and Mg promoter. Detailed characterization revealed that the improved performance of the surfactant-added Mg-promoted catalyst was due to the high dispersion of Ni and MgO particles and the enhanced acidic and basic properties, which affected the number of adsorption sites of NH3 and the kinetic rate-determining step during NH3 decomposition, respectively. The results showed that SAMI could be used to synthesize highly dispersed and active Ni catalysts on zeolites.