PNNL

Abstract

In this work a fixed frequency (2.45?GHz) microwave (MW) was used to synthesis ammonia over Ru/MgO catalysts under ambient atmospheric pressure at 320?°C. The loading of Ru catalyst over MgO was varied at 4?wt% and 10?wt%. The metal support interaction was found to play an important role not only catalytically but also altering the microwave-catalyst interaction affecting the ammonia formation rate. The higher metal loading (10?wt%) produced the most activity, stability, and energy efficiency. It was found the Ru was better dispersed at higher loading which decreased the sintering of the catalyst due to lower microwave energy needed to maintain the reaction temperature. Additional effects from the microwave can include enhanced electron movement and/or electric fields formed between the metal sites of the catalyst. The microwave reactor offers a quick on/off catalyst recovery, within 11?min, compared to thermal convectional Haber Bosch (HB) technology