活性炭载体的超声波处理对钌/活性炭氨合成催化剂催化性能的影响

Effect of Ultrasonic Treatment of Activated Carbon Support on Catalytic Performance of Ru/AC for Ammonia Synthesis

利用超声波处理活性炭,并采用场发射扫描电镜、X射线能谱、N2物理吸附和CO化学吸附等表征手段,考察了超声波处理对活性炭表面形貌、化学组成、表面织构和催化剂钌分散度的影响.以超声波处理的活性炭为载体,以钡和钾为助剂制备了一系列钌基氨合成催化剂,在10·0MPa,10000h-1和400℃的条件下进行了氨合成活性评价.结果表明,超声波处理可有效除去活性炭表面的杂质,提高中孔比表面积占BET比表面积的比例.超声波处理50min的活性炭表面的杂质含量较低,中孔比表面积适中,以其为载体制备的钌基催化剂的活性较高,催化氨合成反应速率可达94·8mmol/(g·h).

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).