Influence of Ethylene Diamine Tetraacetic Acid on the Performance of Magnesia Supported Ru-based Catalysts for Ammonia Synthesis

A series of barium doped nano-magnesia supports (Ba-MgO) modified with ethylene diamine tetraacetic acid (EDTA) were prepared by chemical co-precipitation with an ultrasonic method and were used as supports to prepare Ru-based catalysts. The surface texture and the matter phase of the supports and Ru catalysts were characterized by X-ray diffraction, scanning electron microscope, N2 physical-adsorption, H2 temperature-programmed reduction and inductively coupled plasma-atomic emission spectrometry. The results show that modification of EDTA increases the amount of barium promoter into the support and controls the formation state of barium in supports. The effects of barium promoter content and surface texture in supports achieve an equilibrium state when the molar ratio of EDTA to Ba is 1/2, and the highest activity of Ru/Ba-MgO catalyst is 69.31 mmol·(g·h)−1 under the reaction conditions of 10 MPa, 10 000 h−1 and 698 K.