Effects of Stearic Acid Modification on Ru−Ba−MgO Interaction and the Underlying Mechanism

In this paper, a series of Ru/Ba−MgO−SAx catalysts modified with different stearic acid (SA) contents were prepared by ultrasonic‐strong electrostatic adsorption (SEA) method. X‐ray diffractometer, field emission scanning electron microscope, Fourier‐ transformed infrared spectrometry, temperature‐programmed reduction and other methods were used to characterize the Ba−MgO−SAx and its supported ruthenium‐based catalyst. The results show that the addition of SA significantly improves the surface morphology and texture parameters of Ba−MgO support, changes the single adsorption type of Ba2+ in solution, effectively promotes the addition of promoter Ba, and is also beneficial to the regulation of Ru particles and their dispersion, enhances the interaction between the Ba−MgO and Ru, thereby improving the catalytic activity of ammonia synthesis. When the addition amount of SA is 4 wt%, the catalytic activity is the best, and its outlet ammonia concentration is 16.06 % under the reaction conditions of 450 °C, 10 MPa and 10000 h−1. The addition of stearic acid changed the single form of electrostatic adsorption of Ba2+ in the solution, and the presence of COO− made it form a strong chemical coordination effect with Ba2+, which significantly enhancing the adsorption capacity of the support for promoter Ba, and increasing the electronic density of its supported Ru‐based catalyst, then improving the activity of supported Ru‐based ammonia synthesis.