Efficient plasma-assisted ammonia synthesis over a Ni catalyst supported on citrate-modified MgO-Al2O3

Abstract

Non-thermal plasma-catalyzed ammonia synthesis has garnered significant attention due to its high efficiency under mild conditions. However, developing highly efficient catalysts remains a challenge, and substantial improvements in catalyst performance are still needed. In this study, we developed a novel Ni-MgAl-CA catalyst using a one-pot citrate modification method. Under conditions of 25 kJ/L energy input, the ammonia synthesis rate of the Ni-MgAl-CA catalyst reached 6510 µmol/g/h, with an energy yield of 0.89 g-NH₃/kWh. The catalyst's structure and surface properties were systematically characterized using various techniques. The results demonstrated that citrate modification significantly increased the concentration of oxygen vacancies on the catalyst surface, optimized the microstructure, and promoted the high dispersion of Ni. These oxygen vacancies played a critical role in enhancing the adsorption and activation of nitrogen molecules, as confirmed by experimental and characterization data. These findings confirm that citrate modification is an effective strategy for optimizing the structure and surface properties of catalysts, thereby significantly improving the efficiency of non-thermal plasma-catalyzed ammonia synthesis. This work offers valuable insights into the design and development of more efficient catalysts for ammonia production.