Effect of ultrasonic treatment of activated carbon support on catalytic performance of Ru/AC for ammonia synthesis

The effect of ultrasonic treatment of activated carbon (AC) on its structure, composition, surface texture and ruthenium dispersion on it was investigated by field-emission electron microscopy, energy dispersive Xray spectrometry, N-2 physisorption and CO chemisorption. The results showed that ultrasonic treatment of AC could effectively eliminate the impurities, increase the ratio of mesopore area to BET surface area, decrease the amount of the decomposable surface oxygen groups, and lead to the cleanness of the surface and pores. But the metal dispersion of Ru catalyst did not change greatly when the ultrasonic-treated AC was used as the support. The activity of a series of barium- potassium-promoted Ru/AC catalysts for ammonia synthesis was tested at 10.0 MPa, 10 000 h(-1) and 400 degrees C. The activity of the Ru catatysts was improved greatly using the ultrasonic-treated AC as the support. When AC was treated with ultrasonic for 50 min, the activity of the obtained catalyst was increased from 65.3 to 94.8 mmol/(g center dot h).