Influence of Reaction Conditions and Promoting Role of Ammonia Produced at Higher Temperature Conditions in Its Synthesis Process over Cs‐Ru/MgO Catalyst

Abstract

AbstractCs promoted Ru/MgO catalyst was prepared by an impregnation method using Ru(NO3)3 and Cs(NO3)2 as precursor compounds. The activity measurements for ammonia (NH3) synthesis were carried out in a fixed‐bed flow reactor. A reactant stream of H2 and N2 was used for NH3 synthesis. The influences of reaction temperature, pressure and H2/N2 ratio on the performance of the catalyst were investigated in detail. The relative concentration of H2 and N2 in the reactant stream highly influenced the catalytic activity. The remarkably higher rate of NH3 synthesis was observed for the higher H2/N2 ratio at 400 °C and lower H2 concentration in the reactant stream improved the catalytic activity at lower temperature conditions. A sharp increase in the catalytic activity of Cs−Ru/MgO with an increase in pressure was observed at 400 °C for a reactant stream with higher H2 concentration. Relatively less interaction of H2 with the surface of the catalyst is suggested in the presence of NH3 produced during the reaction conducted at elevated temperature conditions. This less susceptibility for H2 adsorption on the active sites of the catalyst is a plausible reason for a higher rate of NH3 synthesis at higher temperature conditions. We modified the Temkin equation model by considering the adsorbed species on the surface of the catalyst affecting NH3 synthesis.