Removal of Hydrogen Poisoning by Electrostatically Polar MgO Support for Low-Pressure NH₃ Synthesis at a High Rate over the Ru Catalyst

Abstract

The increasing availability of low-cost and low pressure, renewable H2 from wind and solar means has triggered tremendous interest in developing low pressure ammonia synthesis with N2 as the energy carrier as well as fertilizer. As such, Cs-promoted Ru/MgO catalysts used in the Kellogg process show superiority to Fe-based catalysts at milder conditions; however, as known, the surface poisoning of Ru sites by competitive strong H2 dissociative adsorption limits the overall rate. In this study, it is demonstrated that the use of simple electrostatically polar MgO(111) to replace nonpolar MgO as the support can significantly alleviate the hydrogen poisoning and facilitate an unprecedented ammonia production rate by its high intrinsic proton capture ability.