助剂对氨合成Fe_(1-x)O基催化剂母体歧化反应的抑制作用的穆斯堡尔谱研究

MSSBAUER STUDY ON THE INHIBITION OF PROMOTERS ON THE DISPROPORTIONATION OF Fe 1- x O CATALYST FOR AMMONIA SYNTHESIS

Ｆｅ１－ｘＯ基氨合成催化剂具有高活性、易还原的特点［１，２］．但Ｆｅ１－ｘＯ基催化剂的母体Ｆｅ１－ｘＯ在５７０℃以下热力学上的不稳定性是Ｆｅ１－ｘＯ基催化剂使用过程中倍受关注的重要问题之一．作者［３］用真空热处理的方法模拟工业还原过程，结合多晶Ｘ射线...

Fe 1- x O precursor is thermodynamically unstable below 570℃, but the disproportionation behavior of the precursor is inhibited by the promoters which are added into the Fe 1- x O catalyst. When calcium oxide was added into the Fe 1- x O catalyst, calcium ions entered into the Fe 1- x O crystal lattice, decreased the concentration of the defect sites in Fe 1- x O crystal and improved the stability of the Fe 1- x O crystal. The existence of calcium oxide in the Fe 1- x O catalyst can get rid of the occurrence of the precursor disproportionation. The reduction mechanism of Fe 1- x O catalyst promoted by calcium oxide or promoters including calcium oxide is that Fe 1- x O is reduced to α Fe directly. But the reduction of the Fe 1- x O catalyst unpromoted by calcium oxide is related with the reduction conditions. A part of Fe 1- x O is disproportionated to Fe 3O 4 and α Fe at first, and then Fe 3O 4 is reduced to α Fe in the case of large sized catalyst particle or long reduction time; another part of Fe 1- x O is reduced to α Fe directly.