利用浸渍法制备了Co/C合成氨催化剂,考察了助剂Ba、K、La和Ce负载量及反应条件对合成氨性能的影响。试验结果表明:助剂的负载量与Co/C催化剂合成氨性能成山峰形态,Ba、K和Sm的加入显著地提高了催化剂的活性,其中Ba的促进效果最好,其次为Ce〉La〉K,当n(Ba)∶n(Co)为0.8时,催化性能最好。双助剂催化剂的性能明显优于单助剂催化剂,在常压,12 000 h-1和440℃条件下,双助剂Ce0.3-Ba0.8-Co/C催化剂的氨合成活性可达6.56μmol/(s.g)。
A series of Co/C ammonia synthesis catalysts promoted with Ba,K,La and Ce,were prepared by incipient-wetness impregnation method.The influnence of promoters loading and recation parameters on the catalystic activity were investigated in a fixed-bed microreactor.The experimental results indicated that the relation between the promoters loading and catalystic activity presented a volcano type curve,Ba promoter was the most effective one,and the rank was BaCeLaK,the optimum molar ratio of Ba to Co atoms was 0.8.Better activity can be obtained for Co/C catalyst with bi-promoters,ammonia synthesis activity over Ce0.3-Ba0.8-Co/C catalyst can reach 6.56 μmol/(s·g) under 12 000 h-1,440 ℃ and atmospheric pressure.