纳米-微米铁修饰的维氏体氨合成催化剂

我们以商业预还原的维氏体(Fe1-xO)氨合成催化剂为载体,采用Fe(NO)3 ·9H2O和H2C2O4·2H2O进行原位室温固相反应制备纳米铁或微米铁修饰的铁基氨合成催化剂,并通过XRD、SEM、TG-DTG、H2-TPR等进行了表征.结果表明:Fe(NO)3·9H2O和H2C2O4·2H2O室温固相反应完全生成产物Fe2(C2O4)3·5H2O,且产物分散于载体维氏体催化剂表面.通过纳米铁-微米铁的修饰,催化剂的氨合成活性有很大提高且稳定性好.催化剂活性随着Fe负载量的增加先增加后降低,负载量5％时催化活性最好,反应器出口氨浓由450℃(12.4％)、425℃(11.0％)、400℃(9.4％)分别提升至450℃(15.6％)、425℃(14.8％)、400℃(13％).通过一步简单的修饰,维氏体催化剂的氨合成活性提高约25％ ～38％.由于焙烧和还原,生成的Fe1xO或铁粒子与铁催化剂表面发生强相互作用,因此,反应过程中纳米铁或微米铁粒子能稳定存在,催化剂有较高的稳定性.

Modification of Wüstite Based Ammonia Synthesis Catalyst With Fine Fe particles

Commercial and pre-reduced wüstite based catalyst was modified by nano and micro Fe particles via in-situ solidstate reaction of Fe (NO) 3 · 9 H2O with H2C2O4 · 2H2 O at room temperature,and the as-prepared samnples were characterized by means of XRD,SEM,TG-DTG,H2-TPR.Tbe solid-state reaction of Fe(NO3)3 · 9H2O with H2C2O4 · 2H2O at room temperature yields Fe2 (C2O4) 3 · 5 H2O complelely and disperses on the surface of iron catalyst.With modification,significant improvement in ammonia synthesis activity of the catalysts was observed.With the Fe loading of 5％,ammonia concentrations at the outlet of the reactor are improved from 12.4％ to 15.6％ at 450 ℃,11.0％ to 14.8c％ at 425 ℃C and 9.4％ to 13％ at 400 ℃,respectively.Via simple and one-step modification (solid-state reaction),the activity of iron is enhanced by 25％ to 38％.Following calcimtion or reduction,the formed Fe1-xO or Fe particles interact with the surface of ivon catalyst strongly,which stabilizes the nano and micro particles during reaction.As a result,high stability of catalyst is achieved.